Expandable occlusive structure

ABSTRACT

An apparatus for treating a hollow anatomical structure comprises an implant comprising a plurality of bioabsorbable fibers. The implant has a compressed state in which the implant can fit within a cylindrical tube having an inside diameter of 8 French or less. The implant is expandable from the compressed state to an expanded state in which the implant has sufficient size to span the inside diameter of a cylindrical tube having an inside diameter of 12 French or greater.

RELATED APPLICATIONS; PRIORITY

This application claims the benefit under 35 U.S.C. § 119(e) of each ofthe following U.S. Provisional Patent Applications: No. 60/647,173,filed Jan. 25, 2005, titled STRUCTURES FOR PERMANENT OCCLUSION OF AHOLLOW ANATOMICAL STRUCTURE; No. 60/696,165, filed Jul. 1, 2005, titledSTRUCTURES FOR PERMANENT OCCLUSION OF A HOLLOW ANATOMICAL STRUCTURE. Theentirety of each of the above-mentioned provisional patent applicationsis hereby incorporated by reference herein and made a part of thisspecification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to occlusion of a hollow anatomical structure byinserting an occluding device or occluding material into a hollowanatomical structure or surrounding native tissue.

2. Description of the Related Art

The preferred embodiments relate generally to a method and materialcomposition for introduction into a hollow anatomical structure (HAS)with particular relevance to the venous system in the lower extremities.The term “hollow anatomical structure” is a broad term and is used inits ordinary sense, including, without limitation, veins, arteries,gastric structures, coronary structures, pulmonary structures, tubularstructures associated with reproductive organs, and the like. Hollowanatomical structures particularly suited to occlusion by the methods ofpreferred embodiments include veins, preferably veins of the lowerextremities, especially veins in the leg.

The human venous system of the lower extremities consists essentially ofthe superficial venous system and the deep venous system withperforating veins connecting the two systems. The superficial systemincludes the long or great saphenous vein and the small saphenous vein.The deep venous system includes the anterior and posterior tibial veinswhich unite to form the popliteal vein, which in turn becomes thefemoral vein when joined by the short saphenous vein.

The venous system contains numerous one-way valves for directing bloodflow back to the heart. Venous valves are usually bicuspid valves, witheach cusp forming a sack or reservoir for blood. Retrograde blood flowforces the free surfaces of the cusps together to prevent continuedretrograde flow of the blood and allows only antegrade blood flow to theheart. When an incompetent valve is in the flow path, the valve isunable to close because the cusps do not form a proper seal andretrograde flow of the blood cannot be stopped. When a venous valvefails, increased strain and pressure occur within the lower venoussections and overlying tissues, sometimes leading to additional, distalvalvular failure. Two venous conditions or symptoms which often resultfrom valve failure are varicose veins and more symptomatic chronicvenous insufficiency.

The resulting condition is progressive and includes: dilation andtortuosity of the superficial veins of the lower limbs, unsightlydiscoloration, pain, swelling, and possibly ulceration. This failure canalso worsen deep venous reflux and perforator reflux. Current treatmentsof venous insufficiency include surgical procedures such as veinstripping, ligation, and occasionally, vein-segment transplant.

Vein stripping and vein-segment transplant are less-favored treatmentoptions. Vein stripping typically consists of tying off, or ligating,and removal of the saphenous vein. The ligation involves making anincision in the groin and using sutures outside the vein to tie it shut.When the veins are tied off and/or removed, blood flows through the deepveins and back to the heart. This surgery is generally done undergeneral or regional anesthesia during a hospital stay or on anoutpatient basis, depending upon the extent of the procedure. Veinstripping is generally painful and requires a long recovery time. Thisprocedure is less favored and outcomes can be poor. Procedures combiningligation and stripping are sometimes performed, but studies have shownthey offer little advantage over stripping alone. Vein segmenttransplant has been employed in certain organ transplant procedures.However it is not generally employed in the superficial venous system inhumans.

Ligation by ablation involves the cauterization or coagulation ofvascular lumina using thermal energy applied through a deliverycatheter, e.g., electrical energy applied through an electrode device(e.g., a radio frequency or RF device), energy delivered by regular andhigh-frequency ultrasound, or laser energy. An energy delivery device istypically introduced into the vein lumen and positioned so that itcontacts the vein wall. Once properly positioned, the RF, laser,ultrasound, or other energy is applied to the energy delivery device,thereby causing the vein wall to shrink in cross-sectional diameter. Areduction in cross-sectional diameter, for example, from 5 mm (0.2 in)to 1 mm (0.04 in), significantly reduces the flow of blood through thevein and results in an effective ligation. Though not required foreffective ligation, the vein wall can completely collapse, therebyresulting in a full-lumen obstruction that blocks the flow of bloodthrough the vein.

SUMMARY OF THE INVENTION

The preferred embodiments provide materials, structures and methodswhich can be employed to occlude a hollow anatomical structure.Preferably, a bioresorbable material is employed to occlude the hollowanatomical structure. Alternatively, a bioabsorbable, bioerodable,biodegradable, or dissolvable material is employed. In certainembodiments, a biocompatible material that is not bioresorbable,bioabsorbable, bioerodable, biodegradable, or dissolvable is employed.The bioresorbable material is preferably placed in the hollow anatomicalstructure by a minimally invasive method which can be employed forprecisely locating the material within the target lumen.

According to one embodiment, an implant comprises bioresorbablematerials or compounds and is introduced into a hollow anatomicalstructure for occlusion. The materials preferably are non-in-situforming materials. In some embodiments the implant can expand on itsown. In other embodiments the implant can be actuated into an expandedcondition. The implant preferably does not take on a uniform, e.g.,predefined, shape. The implant is deliverable via surgical procedure orcatheter. The materials of the implant preferably are not solvent basedor immediately soluble by fluids in the body. According to oneembodiment, the occlusion is intended to occur over time as the nativefluid (e.g., blood) is limited by the expanding implant such that nativefluid becomes stopped or frustrated and the body's natural healing takesover to occlude the hollow anatomical structure. Active agents includingbut not limited to sclerosants, inflammatory agents, cytokines, growthfactors, clotting factors, tissue attachment factors, plateletactivators, and antibacterial agents can be added to the implant with afocus to elicit and/or favorably alter the body's response and/orcoagulation cascade for healing/occluding the hollow anatomicalstructure.

According to one embodiment, a fixed length or scrunchable lengthimplant can be provided for occlusion. A fibrous mass structure cancomprise fiber filaments. In one embodiment, the fibrous mass structurecan include fibers and/or other components formed from polylactides(polylactic acid) and/or polyglycolides (polyglycolic acid). Asdescribed further below, Polyglycolide (PGA) and Polylactide (PLA) aresynthetic absorbable polymers. These polymers can be prepared from theircyclic diesters lactide and/or glycolide by ring opening polymerizationto synthesize higher molecular weight polymers or by directpolycondensation of lactic acid and/or glycolic acid to synthesize lowmolecular weight polymers. In one embodiment the fibrous mass structurecomprises PGA and PLA filaments. The filament compositions can behomogeneous in some embodiments. In some embodiments, one or moredistinctively unique filament compositions can be used. In someembodiments, filaments can have compositions unique to the distal and/orproximal ends. In some embodiments, the filament composition itself canbe a copolymer of PLA and PGA. Deployment of the implant can comprisescrunching the implant, e.g., contracting the implant along alongitudinal axis to radially expand the implant and/or increase fiberdensity in a given cross section. The scrunching can be performed usinga sleeve, a push rod, a pull string, a pull wire, a push and pull tube,using only external manual compression, and/or combinations thereof. Theimplant can be locked in a deployed configuration (although this is notrequired) by a one way stop, a knot, an adhesive, heating the implant, acutter, a gelling material, and/or combinations thereof. Occlusion ispreferably achieved by blocking blood flow completely (e.g. stopping orpreventing), by limiting the flow of native fluid (e.g. frustrating orinhibiting), by acting as a structure/scaffold for the natural bodyhealing process leading to occlusion, and/or by addition of sclerosantsor other foreign body response proliferative agents or drugs and/orcombinations thereof.

In another embodiment, a sock can be formed weaved, knitted, and/orbraided from any suitable bioresorbable material. In another embodiment,a rigid implant, e.g., a bioresorbable plug, can be coupled withbioresorbable filament materials for occlusion of a hollow anatomicalstructure. The rigid implant preferably has a generally fixed length andshape to partially or entirely block flow acutely in the hollowanatomical structure.

While the methods and materials of preferred embodiments areparticularly preferred for use in occluding veins of the lowerextremities, they can be employed in occluding other hollow anatomicalstructures, including, but not limited to: varicoceles associated withinternal spermatic vein reflux, pelvic congestion associated withovarian vein reflux, abdominal varices, superficial and perforatorveins, hemorrhoids, esophageal varices, fallopian tubes, vas deferens,cardiovascular deformations, vessels in the brain, lumbar arteries,feeding vessels into the aorta to prevent abdominal aortic aneurysm(AAA) graft endoleaks, vessel occlusion for arterio-venousfistula/malformations, cerebral or peripheral vascular aneurysms,aneurismal vessel occlusions. Additionally, these embodiments can alsobe employed in occluding other hollow anatomical structures notnecessarily from inside the lumina, but acting extra-structurally forexample as bulking agents outside the lower esophageal sphincter as inthe treatment of gastroesophageal reflux disease (GERD), forextravascular bulking of incompetent venous valves to improve valvularcoaptation and function in the treatment of varicose veins and chronicvenous insufficiency, or for bulking the area around the coronary valvesfor improved valvular coaptation and function. As well, theseembodiments can be employed not necessarily to occlude hollow anatomicalstructures, but instead for bulking, tissue hardening, and tissuestrengthening for example in modifying the uvula in the treatment ofsleep apnea, for bulking the cardiac muscle in treatment of congestiveheart failure, or for closing the tissue path created by percutaneousvessel access in catheterization procedures.

According to one embodiment, an apparatus for treating a hollowanatomical structure comprises an implant sized for insertion into thehollow anatomical structure. The implant comprises a plurality of loose,bulked fibers. The fibers are formed from one or more bioabsorbablematerials.

According to some variations, the fibers can be radially bulked,randomly arranged, non-knit, and/or non-woven. According to somevariations, the fibers can be formed from an alpha-hydroxy acid, and/orformed from material selected from the group consisting of polyglycolicacid, polyglycolic-co-lactic acid, polylactic-glycolic acid,polyglycolide-co-lactide, and polyglycolide. According to somevariations, the fibers can be from 0.1 denier to 10 denier. The implantcan comprise between 500 and 100,000 fibers, in some embodiments. Thefibers can be joined at a first end portion of the implant. The fiberscan be joined at a second end portion of the implant.

According to some variations, the apparatus comprises a fixation elementconfigured to limit migration of the implant when in the hollowanatomical structure. According to some variations, the apparatusfurther comprises a tether coupled with the implant. The tether can beconfigured to extend beyond at least one end portion of the implant. Thetether extends within the implant in some embodiments. The tether can beformed from a bioabsorbable material having a first bioabsorption rate.The fibers can be formed from a bioabsorbable material having a secondbioabsorption rate. The first bioabsorption rate can be different fromthe second bioabsorption rate. In some embodiments, the firstbioabsorption rate is lower than the second bioabsorption rate. In otherembodiments, the first bioabsorption rate is higher than the secondbioabsorption rate. The fibers can have a bioabsorption time of 2-24weeks after implantation.

According to some variations, the apparatus additionally comprises animplant locking mechanism. In some embodiments, the apparatus comprisesa pull string coupled with the implant. The pull string can beconfigured to extend beyond at least one end portion of the implant. Thepull string can extend within the implant. In some embodiments, theimplant locking mechanism comprises a funnel coupled with the implant.The pull string can be knotted in some embodiments. The pull string cancomprise a plurality of bumps along at least a portion thereof.

According to some variations, the implant further comprises a radiallyexpandable element. The fibers can be positioned generally interior tothe expandable element when implanted in the hollow anatomicalstructure. The fibers can be positioned generally exterior to theexpandable element when implanted in the hollow anatomical structure.The expandable element can extend generally the full length of theimplant. The expandable element can be positioned generally at an endportion of the implant. In some embodiments, the apparatus comprises aexpandable element configured to anchor the implant when inserted withinthe hollow anatomical structure.

According to some variations, the implant additionally comprises a drug.The implant can comprises a sclerosant in some embodiments. According tosome variations, the implant has a first density associated with anunstressed state of the implant, and a higher second density associatedwith a radially compressed state of the implant. According to somevariations, the fibers comprise first fibers having a firstbioabsorption rate and second fibers having a second bioabsorption rate,wherein the first bioabsorption rate differs from the secondbioabsorption rate.

According to another embodiment, an apparatus for treating a hollowanatomical structure comprises a scaffold configured for implantation inthe hollow anatomical structure. At least a section of the scaffoldcomprises a plurality of loose fibers that extend generallylongitudinally and form a number of bends along the length thereof. Thefibers are formed from one or more bioabsorbable materials. According tosome variations, the fibers are randomly arranged in the scaffold. Insome embodiments, at least one of the fibers comprises a number of thebends which are spaced apart along the fiber by one or more distanceswhich are significantly smaller than the length of the fiber. Accordingto some variations, the section of the scaffold is non-knit and/ornon-woven. An outer surface of the scaffold can be abrasive. The fiberscan comprise first fibers having a first bioabsorption rate and secondfibers having a second bioabsorption rate, and the first bioabsorptionrate can differ from the second bioabsorption rate. The fibers can havea bioabsorption time of 2-24 weeks after implantation.

According to another embodiment, a scaffold for treating a hollowanatomical structure comprises a plurality of tortuous, non-knit fibers,the fibers being formed from one or more bioabsorbable materials.According to some variations, the fibers are randomly arranged. Thefibers can be loosely arranged in the scaffold. At least a portion ofthe scaffold can be non-knit and non-woven. The fibers can comprisefirst fibers having a first bioabsorption rate and second fibers havinga second bioabsorption rate, and the first bioabsorption rate can differfrom the second bioabsorption rate. The fibers can have a bioabsorptiontime of 2-24 weeks after implantation.

According to another embodiment, an apparatus for treating a hollowanatomical structure comprises an implant configured for implantation inthe hollow anatomical structure. The implant comprises a pile oftortuous, bioresorbable fibers. According to some variations, the fibersare randomly arranged. The fibers can be loosely arranged in theimplant. At least a portion of the implant can be abrasive.

According to another embodiment, an apparatus for treating a hollowanatomical structure comprises an implant of suitable width forplacement in the hollow anatomical structure. The implant comprises aplurality of textured fibers. The fibers are formed from one or morebioabsorbable materials. According to some variations, the fibers arerandomly arranged. The fibers can be loosely arranged in the implant. Atleast a portion of the implant can be non-knit. At least a portion ofthe implant can be non-woven.

According to another embodiment, an apparatus for treating a hollowanatomical structure comprises an implant sized for insertion into thehollow anatomical structure. The implant comprises a plurality ofcrimped fibers. The fibers are formed from one or more bioabsorbablematerials. According to some variations, the fibers are loosely arrangedin the implant. The fibers are non-knit in some embodiments. The fibersare non-woven in some embodiments.

According to another embodiment, an apparatus for treating a hollowanatomical structure comprises an implant sized for insertion into thehollow anatomical structure. The implant comprises a plurality ofundulating fibers. The fibers are formed from one or more bioabsorbablematerials. According to some variations, the fibers are loosely arrangedin the implant. The fibers can be non-knit. The fibers can be non-woven.At least a portion of an outer surface of the implant can be abrasive.The fibers can comprise first fibers having a first bioabsorption rateand second fibers having a second bioabsorption rate, the firstbioabsorption rate can differ from the second bioabsorption rate. Thefibers can have a bioabsorption time of 2-24 weeks after implantation.

According to another embodiment, an apparatus for treating a hollowanatomical structure comprises a scaffold configured for placement inthe hollow anatomical structure. The scaffold comprises a plurality ofexpandable fibers. The fibers are formed from one or more biodegradablematerials. According to some variations, the fibers are individuallyexpandable. The fibers can be loosely arranged in the implant. At leasta section of the scaffold can be non-knit in some embodiments. At leasta section of the scaffold can be non-woven in some embodiments.

According to another embodiment, an apparatus for treating a hollowanatomical structure comprises an implant comprising a plurality ofbioabsorbable fibers. The implant has a compressed state in which theimplant can fit within a cylindrical tube having an inside diameter of 8French or less. The implant is expandable from the compressed state toan expanded state in which the implant has sufficient size to span theinside diameter of a cylindrical tube having an inside diameter of 24French or greater. According to some variations, the implant hassufficient size, when in the expanded state, to span the inside diameterof a cylindrical tube having an inside diameter of 24-36 French. In someembodiments, the implant has sufficient size, when in the expandedstate, to span the inside diameter of a cylindrical tube having aninside diameter of 12-60 French. The implant can fit within acylindrical tube having an inside diameter of 6-8 French when in thecompressed state in some embodiments. The implant can comprise aplurality of undulating fibers. At least a section of the implant can benon-knit. At least a section of the implant can be non-woven. Theimplant can comprise a fixation element configured to limit migration ofthe implant when in the hollow anatomical structure. The implant can beexpandable such that the implant tends toward the expanded state in theabsence of external forces.

According to another embodiment, an apparatus for treating a hollowanatomical structure comprises an implant comprising a plurality ofbioabsorbable fibers. The implant has a compressed state in which theimplant can pass through a cylindrical tube having an inside diameter of8 French or less. The implant is expandable from the compressed state toa treatment state in which the implant has a transverse size which issufficiently large to occupy an adult human greater saphenous vein ofaverage size. According to some variations, the implant can pass througha cylindrical tube having an inside diameter of 6-8 French when in thecompressed state. The implant can comprise a plurality of undulatingfibers. At least a section of the implant can be non-knit. At least asection of the implant can be non-woven. The implant can comprise afixation element configured to limit migration of the implant when inthe hollow anatomical structure. The implant can be expandable such thatthe implant tends toward the expanded state in the absence of externalforces.

According to another embodiment, a method of treating a hollowanatomical structure having a diameter of 4 mm or more comprisesinserting into the hollow anatomical structure a catheter having a sizeof 8 French or less. A bioabsorbable fibrous implant is passed throughthe catheter and into the hollow anatomical structure. With the implant,the patency of the hollow anatomical structure is reduced. According tosome variations, the method further comprises occluding the hollowanatomical structure with the implant. The implant can be expanded to atreatment state within the hollow anatomical structure in some methods.The method can included promoting occlusive ingrowth with the implantwhen the implant is in the hollow anatomical structure. The hollowanatomical structure can comprise a vein. In some embodiments, thehollow anatomical structure comprises a greater saphenous vein.Inserting the catheter can comprise inserting the catheter at aninsertion site spaced from the sapheno-femoral junction, and furthercomprise advancing the implant from the insertion site to thesapheno-femoral junction. The hollow anatomical structure can have adiameter of 4-12 mm in some embodiments. In some embodiments, the hollowanatomical structure can have a diameter of 4-20 mm.

According to another embodiment, a method of treating a vein comprisesaccessing the vein at an access point spaced from a sapheno-femoraljunction. A bioabsorbable fibrous body is implanted into the veinthrough the access point. The body is moved in the vein toward thesapheno-femoral junction. According to some variations, the methodadditionally comprises securing the body in the hollow anatomicalstructure to limit migration of the body within the vein. A sheath canbe inserted through the access point and the body can be pushed with apushrod through the sheath into the vein in some methods. A heattreatment can be performed on the vein, the heat treatment can compriseone or more of delivering radio frequency energy, delivering heat energyfrom a resistive element, and delivering energy from a laser. The methodcan additionally comprise moving an end of the body in the vein to thesapheno-femoral junction.

According to another embodiment, a method of treating a hollowanatomical structure comprises delivering into the hollow anatomicalstructure an implant comprising a plurality of loose tortuous fibers.The fibers are formed from one or more bioabsorbable materials.According to some variations, the method additionally comprises securingthe implant in the hollow anatomical structure to limit migration of theimplant within the hollow anatomical structure.

According to another embodiment, a kit for treating a hollow anatomicalstructure comprises a bioabsorbable fibrous implant sized for insertioninto the hollow anatomical structure. A sheath is sized for insertioninto the hollow anatomical structure. The sheath has an outer diameterand an inner diameter. The inner diameter is configured to receive theimplant for delivery of the implant into the hollow anatomicalstructure. A pushrod is sized for insertion into the sheath andconfigured to advance the implant through the sheath for delivery of theimplant into the hollow anatomical structure. According to somevariations, the sheath comprises an abrasive element on the outerdiameter. The abrasive element can be configured to engage a surface ofthe hollow anatomical structure when the sheath is inserted within thehollow anatomical structure. The kit can additionally comprise animplant locking mechanism. The implant locking mechanism can comprise apull string configured to be coupled with the implant. The implantlocking mechanism can comprise a funnel coupled with the implant. Thepull string can be knotted. The pull string can comprise a plurality ofbumps along at least a portion thereof.

According to another embodiment, a system for treating a hollowanatomical structure comprises a bioabsorbable fibrous implant sized forinsertion into the hollow anatomical structure. A continuous feedmechanism is configured to deliver the implant into the hollowanatomical structure.

According to another embodiment, a method of treating a hollowanatomical structure of a patient comprises implanting a bioabsorbablefibrous body in the hollow anatomical structure. The body is secured inthe hollow anatomical structure to limit migration of the body withinthe hollow anatomical structure. According to some variations, securingthe body comprises anchoring the body at an access site of the hollowanatomical structure. In some embodiments, the method further comprisespositioning the body so that a portion of the body extends out of thehollow anatomical structure through the skin of the patient at an accesssite on the skin. The body can further comprise a tether, and the methodcan further comprise trimming an end portion of the body so that it issubstantially flush with the skin and so that the tether extends beyondthe body through the access site. The tether can be secured near theaccess site. Securing the body can comprise implanting an expandableanchor near the body in the hollow anatomical structure. Securing thebody can comprise thermally shrinking the hollow anatomical structurenear an implant location in the hollow anatomical structure, andimplanting the body can comprise implanting the body at the implantlocation. Securing the body can comprise securing the body with afenestration anchor. Securing the body can comprise anchoring the bodyat a percutaneous retrograde access site.

According to another embodiment, an apparatus for treating a hollowanatomical structure comprises a bioabsorbable fibrous body. A fixationmember is associated with the body and configured to limit migration ofthe body when implanted in the hollow anatomical structure. According tosome variations, the fixation member comprises a tether. The fixationmember can comprise an anchor. The fixation member can comprise anexpandable element. The fixation member can comprise a braid. Thefixation member can be bioabsorbable. The fixation member can have afirst bioabsorption rate, the body can have a second bioabsorption rate,and the first bioabsorption rate can be different from the secondbioabsorption rate. The first bioabsorption rate can be lower than thesecond bioabsorption rate. The first bioabsorption rate can be higherthan the second bioabsorption rate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a portion of the saphenous and femoral venous systems.

FIG. 2A depicts one embodiment of an implant comprising a fibrous massstructure for occlusion of a hollow anatomical structure, such as avein, the fibrous mass structure is shown in a generally unstressed,expanded configuration.

FIG. 2B depicts a fiber of the implant of FIG. 2A showing bends in thefiber in the generally unstressed, expanded configuration.

FIG. 2C depicts the fibrous mass structure implant of FIG. 2A in agenerally low-profile, compressed configuration.

FIG. 2D depicts a fiber of the implant of FIG. 2C showing bends in thefiber in the generally low-profile, compressed configuration.

FIG. 2E depicts a portion of one embodiment of a method for delivering afibrous mass structure to a hollow anatomical structure, showing acatheter or delivery sheath inserted into a hollow anatomical structure.

FIG. 2F depicts an implant in a low-profile configuration advanced witha pushrod through the catheter or delivery sheath according to themethod of FIG. 2E.

FIG. 2G depicts the implant in an expanded configuration within thehollow anatomical structure and the delivery catheter or sheath beingwithdrawn from the hollow anatomical structure according to the methodof FIG. 2E.

FIG. 3 depicts the fibrous mass structure in two use conditions.

FIG. 4 depicts the fibrous mass structure in two use conditions, in afolding use context.

FIG. 5 depicts another fibrous mass structure with an interlaced pullmember.

FIG. 6 illustrates one process of delivering a fibrous mass structureinto a hollow anatomical structure such as a vein.

FIG. 7 illustrates the use of a ring locking mechanism in deploying afibrous mass structure.

FIG. 8 illustrates the use of a knot locking mechanism in deploying afibrous mass structure.

FIG. 9A illustrates the use of a ratchet locking mechanism in deployinga fibrous mass structure.

FIG. 9B illustrates another method and apparatus for occlusion of ahollow anatomical structure such as a vein.

FIG. 10 illustrates another method and apparatus for occlusion of ahollow anatomical structure such as a vein.

FIG. 11 illustrates a woven sock for occlusion of a hollow anatomicalstructure such as a vein.

FIG. 12 illustrates another method and apparatus for occlusion of ahollow anatomical structure such as a vein.

FIG. 13 illustrates further details of a fibrous mass structure.

FIG. 14 illustrates fibers for use in a fibrous mass structure.

FIG. 15 illustrates fibers for use in a fibrous mass structure.

FIG. 16 illustrates fibers for use in a fibrous mass structure.

FIG. 17 illustrates fibers for use in a fibrous mass structure.

FIG. 18 is a schematic cross-sectional view of one embodiment of acontinuous feed hollow anatomical structure occlusion system in a firstposition.

FIG. 19 is a schematic cross-sectional view of the system of FIG. 18 ina second position, a first segment of fibrous mass structure having beendeployed.

FIG. 20 is a schematic cross-sectional view of the system of FIG. 18 ina third position, illustrating the retraction of a pusher rod.

FIG. 21 is a schematic cross-sectional view of an alternative embodimentof a continuous feed hollow anatomical structure occlusion system.

FIG. 22 is a schematic cross-sectional view of an alternative embodimentof a continuous feed hollow anatomical structure occlusion system.

FIG. 23 is a distal elevation view of a distal end of the inner sheathof the device of FIG. 22.

FIGS. 24-26 illustrate a continuous feed hollow anatomical structureocclusion system.

FIGS. 27 a-27 c illustrate a pistol grip handle used for delivery of afibrous mass structure.

FIG. 28 illustrate the pistol grip handle with the fibrous massstructure on a coil.

FIG. 29 illustrates an overlapping delivery configuration of the fibrousmass structure.

FIG. 30 illustrates a scraping end of a delivery sheath.

FIG. 31 illustrates several abrasive elements for contacting an innersurface of a hollow anatomical structure.

FIGS. 32-35 illustrate one method of fixation of an implant at an accesssite location according to one embodiment.

FIGS. 36A-F illustrate several alternative fixation techniques accordingto several embodiments.

FIGS. 37A-E illustrate several alternative fixation methods according toseveral embodiments.

FIG. 38 illustrates a tether string comprising a needle point accordingto one embodiment.

FIG. 39 illustrates a tether string coupled with an implant at one ormore locations according to several embodiments.

FIGS. 40A-C illustrate a blunt tip “V”-shaped fixation element accordingto one embodiment.

FIG. 41 illustrates a “U”-shaped fixation element according to oneembodiment.

FIGS. 42A-C illustrate an expandable hoop shaped fixation elementaccording to one embodiment.

FIGS. 43A-B illustrate an expandable sine wave shaped stent fixationelement according to one embodiment.

FIGS. 44A-B illustrate an expandable diamond shaped stent fixationelement according to one embodiment.

FIGS. 45A-C illustrate an expandable stent fixation element according toone embodiment.

FIGS. 46A-C illustrate an expandable braided stent fixation elementaccording to one embodiment.

FIGS. 47A-B illustrate an expandable multifilament fixation elementaccording to one embodiment.

FIGS. 48A-C illustrate one embodiment of a method of providing bulkingmaterial near a hollow anatomical structure.

FIG. 49 illustrates a biodegradable clip fixation element according toone embodiment.

FIG. 50 illustrates a fenestration technique according to oneembodiment.

FIGS. 51A-H illustrate several coils configured for use in afenestration fixation technique according to several embodiments.

FIGS. 52A-B illustrate a polymer coil according to one fixationembodiment.

FIGS. 53A-B illustrate a barbed suture according to one fixationembodiment.

FIGS. 54A-C illustrate a multi-pronged expandable fixation elementaccording to one embodiment.

FIGS. 55A-B illustrate a wedge-type fixation element according to oneembodiment.

FIGS. 56A-B illustrate a wedge-type fixation element according toanother embodiment.

FIGS. 57A-C illustrate a “T”-shaped wedge-type fixation elementaccording to another embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description and examples illustrate preferred embodimentsof the present invention in detail. Those of skill in the art willrecognize that there are numerous variations and modifications of thisinvention that are encompassed by its scope. Accordingly, thedescription of a preferred embodiment should not be deemed to limit thescope of the present invention.

Methods, systems, and apparatuses for occluding a hollow anatomicalstructure (e.g., FIG. 1) in a patient or subject using an occludingdevice or occluding material are provided. The terms “subject” and“patient” as used herein, refer to animals, such as mammals. Forexample, mammals contemplated by one skilled in the art include humans,primates, dogs, cats, sheep, cattle, goats, pigs, horses, mice, rats,rabbits, guinea pigs, and the like. The terms “subject” and “patient”are used interchangeably.

The terms “occluding device” and “occluding material” as used herein,are broad terms and are used in their ordinary sense, including, withoutlimitation, a substance or device that is capable of occluding orcausing occlusion of a hollow anatomical structure. Occluding materialsor occluding devices can be formed or fabricated ex situ, or formed insitu (e.g., by curing of a prepolymer or uncured polymer). The term“occluding material” as employed herein, includes prepolymers, uncuredpolymers, unsolidifed materials, as well as occluding materials insertedinto a patient in polymerized, precured or solidified form. Biologicmaterials, e.g, gelatin, thrombin, can also be used separately or incombination with the occlusive materials. Bioresorbable materials areparticularly preferred occluding materials, although other materials canalso be used as desired. For example, in one embodiment, the fibrousmass structure can include fibers and/or other components formed frompolylactides (PLA) and/or polyglycolides (PGA) or copolymers thereof.

Occluding can include, but is not limited to, blocking by insertion of aplug or other structure into the hollow anatomical structure (e.g.,FIG. 1) that prevents or inhibits flow therethrough, adhering oppositewalls of the hollow anatomical structure together so as to prevent orinhibit flow therethrough, compressing the walls of the hollowanatomical structure together so as to prevent or inhibit flowtherethrough, or initiating a physiological reaction to an applied forceor substance (e.g., energy, chemicals, drugs, physical contact, pressureor the like) that causes flow through the hollow anatomical structure tobe inhibited or prevented (e.g., formation of a fibrotic plug, or growthof connective tissue). Occlusion can be immediate, or onset of occlusioncan be delayed. Occlusion can be partial (permitting a reduced flowthrough the hollow anatomical structure) or complete (permitting no flowthrough the hollow anatomical structure). Occlusion can be permanent ortemporary. Occlusion can be affected by resorption characteristics ofthe material. Occlusion can result in physical change or damage to thehollow anatomical structure (e.g., tissue fibrosis, or necrosis), or canblock the hollow anatomical structure without substantial physicalchange (e.g., a biocompatible plug). The mechanisms by which occlusioncan occur include but are not limited to formation of an organizedfibrotic occlusion resulting from the body's natural foreign bodyhealing response, formation of a wound or damage to tissue, expansion ofthe occluding device or occluding material, release of a chemical orbioactive agent (e.g., a sclerosant, inflammatory agent, cytokine,growth factor, clotting factor, tissue attachment factor, or otheragent) from the occluding device or occluding material,venoconstriction, compression, and ligation. Other mechanisms, forms,and effects of occlusion will be appreciated by those of skill in theart.

Occlusive Structures

FIGS. 2A-D show one embodiment of an apparatus for treating a hollowanatomical structure. The apparatus comprises an implant 10 sized forinsertion into the hollow anatomical structure 20. The term “implant” asused herein, is a broad term and is used in its ordinary sense,including, without limitation, a substance, structure or device that iscapable of being implanted within a hollow anatomical structure. Theimplant 10 comprises a fibrous mass structure 12 including a pluralityfibers 14. The implant 10 has a first density associated with anunstressed state of the implant 10 as shown in FIGS. 2A-B. The implant10 has a higher second density associated with a radially compressedstate of the implant 10 as shown in FIGS. 2C-D. The implant 10preferably is compressible and self-expanding. For example, the implant10 comprises a plurality of expandable fibers 14 that can expand fromthe compressed state of FIGS. 2C-D to the unstressed state of FIGS.2A-B.

Expansion of the implant 10 is facilitated by the crimped configurationof individual fibers 14 of the implant 10. As shown in FIGS. 2A-D, thefibers 14 are crimped in both the compressed and unstressed state. Theimplant 10 comprises a plurality of loose, bulked fibers 14. The term“loose” as used herein with respect to the fibers 14, is a broad termand is used in its ordinary sense, including, without limitation, notsecurely attached as a whole (allowing for interconnection, joining,bundling or tying, in some locations, of a number (e.g. less than 50%)of the fibers short of the whole collection) along all or a significantportion (e.g. more than 10%) of the length of the implant 10. The term“bulked” as used herein with respect to the fibers 14, is a broad termand is used in its ordinary sense, including, without limitation,tending to occupy or create a greater volume, when placed among acollection of fibers, than a substantially straight fiber of similardenier or cross-sectional size.

The implant 10 additionally comprises a plurality of textured fibers 14.The individual fibers 14 of the implant 10 preferably are crimped,bulked and/or deformed by various commonly known fiber texturingprocessing techniques, such as, for example, hot air crimping,mechanical stuffer box crimping, false twist texturing, stretchtexturing, draw texturing or other processes which allow the fibers 14themselves to self expand, thus bulking and expanding the fibrous mass12. Also, this texturing slows the flow of blood acutely whichfacilitates good tissue ingrowth and ultimate durable fibroticocclusion. Also, this texturing allows the implant 10 to be deliverablein low-profile and expand up to fill the target hollow anatomicalstructure 20. One process for making a fibrous implant 10 includesrepeated stretching of the textured yarn to “unlock” the texture thathas been associated with the yarn. The fibers 14 are mechanically andrepeatedly stretched. Stretching the fibers 14 helps them regain theirbulk following texturing.

Thus, as shown in FIGS. 2A-D, the implant 10 preferably comprises ascaffold of loose fibers 14 that extend generally longitudinally andform a number of bends along the length thereof formed through thetexturing and stretching processes. The term “scaffold” as used herein,is a broad term and is used in its ordinary sense, including, withoutlimitation, a supporting framework or lattice which is possibly but notnecessarily temporary in nature. The term “bends” as used herein withrespect to the fibers 14, is a broad term and is used in its ordinarysense, including, without limitation, curved or angled changes ofdirection (e.g., apices) and/or the portions of the fibers that extendbetween the changes of direction.

The fibers 14 preferably are radially bulked. The term “radially bulked”as used herein with respect to the fibers 14, is a broad term and isused in its ordinary sense, including, tending to occupy or create bulkor volume in the radial direction (generally orthogonal or transverse tothe long axis of the fiber when laid substantially straight) beyond thecross-section of the fiber. For example, because the fibers 14 have acrimped, bent, or undulating configuration as a result of the texturingand stretching processes, the fibers 14 collectively and/or individuallybecome relatively shorter in the longitudinal direction, and relativelythicker in the radial direction. The fibers 14 thus create a scaffoldhaving high void content and relatively low density. The crimpedconfiguration of the fibers 14 promotes the self-expanding property ofthe fibers 14. Fibers 14 are biased towards the expanded state such thatthe implant 10 is expandable.

The fibers 14 can be from 0.1 denier to 10 denier and the implant 10 cancomprise between 500 and 100,000 fibers in some embodiments. The implant10 can comprise between 500 and 500,000 fibers in some embodiments.These fibers 14 are preferably loose, non-knit, and/or non-woven. Forexample, in some embodiments, the fibers 14 are not rigidly fastened orsecurely attached to each other. The fibers 14 preferably are relativelyfree to move and are generally not confined or restrained relative toeach other along the length of the implant 10. In some embodiments, thefibers 14 can be joined at a first end portion of the implant 10. Insome embodiments, the fibers 14 can be joined at a second end portion ofthe implant 10. Fiber sizes and configurations are described in moredetail below.

The fibers 14 preferably are formed from one or more bioabsorbableand/or biodegradable materials. The term “bioabsorbable” as used herein,is a broad term and is used in its ordinary sense, including, withoutlimitation, capable of being taken in and made part of an existentbiological whole. The term “biodegradable” as used herein, is a broadterm and is used in its ordinary sense, including, without limitation,capable of being broken down especially into innocuous products by theaction of living things. In some embodiments, the fibers 14 areindividually expandable. In some embodiments, the fibers 14 can beformed from an alpha-hydroxy acid, and/or formed from material selectedfrom the group consisting of polyglycolic acid, polyglycolic-co-lacticacid, polylactic-glycolic acid, polyglycolide-co-lactide, andpolyglycolide. These and other suitable materials are described in moredetail below. The fibers 14 can comprise first fibers having a firstbioabsorption rate and second fibers having a second bioabsorption rate,where the first bioabsorption rate differs from the second bioabsorptionrate.

In some embodiments, the implant 10 can be radially expanded, foldedover, bunched and/or tangled as shown in FIGS. 3-5. Additionally, oneembodiment of a method of delivering an implant 10 is shown in FIG. 6and described in more detail below.

In some embodiments, the apparatus can comprise a fixation elementconfigured to limit migration of the implant 10 when in the hollowanatomical structure. The term “fixation element” as used herein, is abroad term and is used in its ordinary sense, including, withoutlimitation, a device which tends to reduce or eliminate movement of a anobject placed within a hollow anatomical structure. For example, theapparatus can comprise a tether coupled with the implant.

In some embodiments, the apparatus additionally comprises an implantlocking mechanism, as discussed in more detail below with reference toFIGS. 7-9. The term “locking mechanism” as used herein, is a broad termand is used in its ordinary sense, including, without limitation, astructure for forming an interlocking or entanglement of elements orparts; a structure or device to secure in position, hold, or control aconfiguration; a structure to fix in place. For example, the apparatuscan comprise a pull string 30 coupled with the implant 10 and configuredto extend beyond at least one end portion of the implant 10. In someembodiments, the pull string 30 can position the implant 10 in anexpanded configuration within a hollow anatomical structure.

As is described further below, in some embodiments, the implant 10further comprises-a radially expandable-element. In some embodiments,the fibers 14 can be positioned generally interior to the expandableelement when implanted in the hollow anatomical structure 20. In someembodiments, the implant 10 additionally comprises a drug and/or asclerosant. In some embodiments, an outer surface of the scaffold can beabrasive. The term “abrasive” as used herein, is a broad term and isused in its ordinary sense, including, without limitation configured toirritate, rub or wear away for example by friction; or with reference tothe outer surface of the implant 10, sufficiently abrasive to denude anendothelial layer when moved while in contact with the layer.

FIGS. 2E-G illustrate one embodiment of a method of delivering animplant 10 into a hollow anatomical structure 20. The method is suitablefor delivering one or more of a number of implants disclosed herein. Asshown in FIG. 2E, a delivery catheter and/or sheath 16 is inserted intoa hollow anatomical structure 20. According to one embodiment, thedelivery catheter 16 preferably is 8 F or smaller. In some embodiments,the delivery catheter is 6 F. The hollow anatomical structure 20 has aninner diameter preferably 4 mm or larger. In some embodiments, the innerdiameter of the hollow anatomical structure is 4-12 mm. In someembodiments, the inner diameter of the hollow anatomical structure is4-20 mm. The hollow anatomical structure can be a vein, e.g., thegreater saphenous vein, or short saphenous vein or other hollowanatomical structures, such as, for example, a fallopian tube, ovarianvein, or internal spermatic vein.

An implant 10, e.g., a fibrous mass structure 12, is loaded into thedelivery catheter 16 as shown in FIG. 2F. The implant 10 preferablytakes on a compressed configuration (such as that shown in FIG. 2C) whenin the delivery catheter 16. The implant 10 is pushed to a distal endportion of the delivery catheter 16. In some embodiments, a pushrod 18can be used to advance the implant 10. Pushrods 18 are described in moredetail below. For example, in some embodiments, an implant 10 can befolded over its distal end to form a fold or apex at an intermediateportion of the implant 10. The distal tip of the pushrod 18 can engagethe fold or apex to facilitate pushing the implant 10 into the hollowanatomical structure 20.

As shown in FIG. 2G, the implant 10 is pushed out of the distal endportion of the delivery catheter 16 and-into the hollow anatomicalstructure 20. In some embodiments, the pushrod 18 can be used to urgethe implant 10 distally. In some other embodiments, the pushrod 18 canbe held generally stationary and the delivery catheter 16 can be pulledproximally to deliver the implant 10 into the hollow anatomicalstructure 20. As shown in FIG. 2G, the implant 10 preferably takes on atreatment state or expanded configuration (such as that shown in FIG.2A) when in place in the hollow anatomical structure 20. Theself-expanding properties of the fibers 14 and the implant 10 cause itto expand and span the hollow anatomical structure 20. The implant 10preferably forms a scaffold for occlusive ingrowth and clotting in theimplant 10, eventually forming a durable occlusion of the hollowanatomical structure 20 as discussed in further detail herein. Whentreating a saphenous vein such as the greater saphenous vein, thecatheter 16 can be inserted into the hollow anatomical structure at aninsertion site remote from the sapheno-femoral junction within thegreater saphenous vein and advanced toward or to the sapheno-femoraljunction. The implant 10 is then advanced through the catheter toward orto the sapheno-femoral junction. If desired, the implant 10 can beplaced in the vein such that it extends from the sapheno-femoraljunction all the way to the insertion site.

Additionally, one or more of the methods described herein can furthercomprise moving the implant 10 within the hollow anatomical structure 20(either before initial implantation, within the catheter 16, or afterinitial implantation), into a final treatment position. Thus, it will beappreciated that the implant 10 and/or fibrous mass structure 12 ofFIGS. 2A-D, and other implants 10 disclosed herein, can have acompressed state (e.g. FIG. 2C) in which the implant 10 fits within(and/or can pass through) a cylindrical tube (e.g. delivery catheter)having an inner diameter of 8 F or less. In some embodiments, the innerdiameter of the cylindrical tube is 6-8 F. Accordingly, the implant 10preferably can expand from the compressed state to an expanded state.(e.g. FIG. 2A) wherein the implant 10 has sufficient size to span theinner diameter of a hollow anatomical structure 20 of 4-12 mm, and/orspan the inner diameter of a cylindrical tube having an inner diameterof 24 F or greater. In some embodiments, the implant 10 has sufficientsize to span the inner diameter of a hollow anatomical structure 20 of4-20 mm. In some embodiments, the implant 10 can span the inner diameterof a cylindrical tube having an inner diameter of between 24-36 F. Insome embodiments, the implant 10 can span the inner diameter of acylindrical tube having an inner diameter of between 12-60 F.Alternatively, in some embodiments, the implant 10 can expand to atreatment state wherein the implant 10 has a transverse sizesufficiently large to occupy an adult human greater saphenous vein ofaverage size or larger.

In one embodiment, the implant 10 has a compressed state in which theimplant 10 can fit within a cylindrical tube having an inside diameterof 8 French or less. The implant 10 preferably is expandable from thecompressed state to a treatment state in which the implant 10 has atransverse size which is sufficiently large to occupy an adult humangreater saphenous vein of average size. For example, in someembodiments, the implant 10 preferably is expandable from the compressedstate to an expanded state in which the implant 10 has sufficient sizeto span the inside diameter of a cylindrical tube having an insidediameter of 24 French or greater. The implant 10 preferably hassufficient size, when in the expanded state, to span the inside diameterof a cylindrical tube having an inside diameter of 24-36 French. In someembodiments, the implant 10 preferably has sufficient size, when in theexpanded state, to span the inside diameter of a cylindrical tube havingan inside diameter of 12-60 French. The implant 10 can fit within acylindrical tube having an inside diameter of 6-8 French when in thecompressed state in some embodiments. The implant 10 can beself-expanding such that the implant tends toward the expanded state inthe absence of external forces.

According to one embodiment, an occluding device or implant 10 comprisesa fibrous mass structure 12, as shown in FIGS. 2-9A. The fibrous massstructure 12 can include one or more strands 14 of fiber material. Thefibrous mass structure 12 can be positioned within a delivery sheath 16for delivery into a hollow anatomical structure 20. As the deliverysheath 16 is withdrawn, the fibrous mass structure 12 is exposed withinthe hollow anatomical structure 20. The fibrous mass structure 12preferably occludes the hollow anatomical structure 20 as will bedescribed further below.

One advantage of using a fibrous mass structure 12 for occluding ahollow anatomical structure 20 is the ability to treat structures nearnerves or the skin without concern for heat damage, parasthesia, skinburn or damage to other adjacent anatomical structures requiringprotection from heat or other perivascular damage. In one embodiment,using a fibrous mass structure 12 is particularly useful for treatinghollow anatomical vessels below the knee where the greater saphenousvein runs close to nerves. Additionally, in some embodiments, using afibrous mass structure 12 can avoid the need to use tumescent anesthesiafor hollow anatomical structure compression and pain management duringthe procedure. In one embodiment, general and/or regional anesthesia isnot used. In one embodiment, local or topical anesthesia and/orsemi-conscious sedation can be used for implantation of a fibrous massstructure 12. In some embodiments, the fibrous mass structure 12 isparticularly well suited for performing occlusions of tortuous veins.Additionally, a bioresorbable occluder can advantageously be used in theinternal spermatic vein to treat varicoceles and the ovarian vein totreat pelvic congestion syndrome or fallopian tube occlusion and/or vasdeferens for permanent contraception.

Any suitable materials can be employed to form the fibrous massstructure 12. These materials are preferably bioresorbable materialsthat can be fabricated into a desired form for insertion into the hollowanatomical structure. A suitable size and shape of the material can beselected according to the hollow anatomical structure to be occluded.The fibrous mass structure 12 can comprise a composite of two or morematerials or a single copolymer with different bioresorption rates,different biodegradation rates, solubilities, porosities, strengths,rigidities, or the like. Materials and methods for manufacturing animplant will be described in more detail below.

The fibrous mass structure 12 preferably is long enough to treat adesired length of hollow anatomical structure with a single device. Insome embodiments, the length of the fibrous mass structure 12 is betweenabout 1 cm, or less, to about 60 cm, or more. In some embodiments, it isdesirable to have a length short enough to treat a small section near,for example, the saphenofemoral junction. In some embodiments, it isdesirable to have a length long enough to treat an entire vein from thegroin to the knee. In some embodiments, it is desirable to have a lengthlong enough to treat an entire vein from the groin to the ankle.

As shown in FIGS. 2-9A, in one embodiment, the fibrous mass structure 12comprises a plurality of long, continuous, thin fibers 14 (which, insome embodiments can be plied into a yarn). Alternatively, the fibrousmass structure 12 can comprise a plurality of thin staple fibers, withlengths ranging from 2 cm to 100 cm. The fibrous mass structure 12 canhave a first configuration for delivery and a second configuration foroccluding the hollow anatomical structure 20. In the firstconfiguration, the fibrous mass structure 12 has a relativelylow-profile. The cross-sectional area of the fibrous mass structure 12preferably is small enough to facilitate delivery through a deliverydevice, such as a delivery sheath 16. In the second configuration, thefibrous mass structure 12 has a relatively expanded profile.

The individual fibers 14 of the implant 10 and/or fibrous mass structure12 are crimped, bulked and/or deformed by various commonly known fiberprocessing techniques, such as, for example, hot air crimping,mechanical stuffer box crimping, false twist texturing, stretchtexturing, draw texturing or other processes which allow the fibers 14themselves to self expand, thus bulking and expanding the fibrous mass12. Alternatively, the fibrous mass 12 itself can be heat set, solventcast, spin cast, molded, extruded, solvent sprayed, melt spun, electrospun, etc. in the expanded state.

For example, in some embodiments, fiber texturing can be advantageousacutely for self-expansion and/or volume filling. Fiber texturing canprovide an implant 10 with a high void content scaffold which allows theimplant 10 to space fill without over packing. Implants 10 comprisingtextured fibers 14 can improve patient comfort and can be importantchronically for biologic occlusion, providing tissue scaffolding, and/orenabling durable occlusion. The texture of the fibers 14 facilitates theself expansion, volume filling and occlusive/scaffold properties of theimplant 10. Also, this texturing slows the flow of blood acutely whichfacilitates good tissue ingrowth and ultimate durable fibroticocclusion. Also, this texturing allows the implant 10 to be deliverablein low-profile and expand up to fill the target hollow anatomicalstructure 20. Texturing adds bulk to the fiber 14 and random arrangementof the fibers 14 further enhances the self-expansion, volume filling andocclusive/scaffold properties of the implant 10. Texturing can be doneby S&Z false twist texturing with or without air tack, stuffer boxtexturing, air-jet texturing (entangling), stretch texturing, drawtexturing or other commonly used textile yarn texturing methods.

As yarn is produced, emerging filaments or fibers preferably coolrapidly and solidify; they can also be ‘drawn’ by taking them up at afaster rate than that of the supply. Drawing can stabilize the molecularstructure and strengthen the yarn by improving the molecularorientation. A spinneret can be used to produce a number of fine streamsthat can be solidified to make filaments or fibers. The filaments aredrawn to orient the molecular structure and the melts are solidified bycooling them below their melting point (melt spinning). The flowingpolymer preferably is filtered to prevent lumps, such as gels andforeign bodies, from clogging the holes in the spinneret.

The rate of heat flow away from the extruded filaments leaving thespinneret helps to determine the morphological structure of the yarn.Morphology relates to the degree of crystallinity and orientation. Athigh speeds, the shear rate in the extrusion zone (which is a functionof the filament velocity) also affects the morphological structure. Theamount of subsequent drawing of these filaments yet further affects theproperties of the yarn. Draw ratios affect the strength of the partiallyoriented yarn (POY). The strength of the POY produced at low draw ratiosmay be insufficient for high speed texturing and thus it may bedesirable to draw at the texturing stage to increase the filamentstrength. Thus, when the POY is being produced for draw-texturing, thetexturing speeds in effect become linked to the extrusion speeds.Filaments are often wrapped around rotating cylinders or godets.

In most texturing systems, filaments or fibers are heat set into somesort of crimped or convoluted form, such that each filament or fiber isheld as separate from its neighbors as possible. For filaments or fibersthat cannot be heat set, it is possible to tangle the fibers to lockthem mechanically. An example of this is air-jet texturing. Sometimes itis desirable to combine air-jet with false twist texturing. Airjettexturing gives a product that is nearer to a staple yarn than is afalse-twist textured yarn.

Texturing via stuffer box, air jet and S&Z false twist is well known inthe art. Useful parameters are the frequency of the crimp and crimpretention. The ASTM standard on crimp recovery (retention) is D4031,which defines crimp contraction, in this context, as an indicator ofcrimp capacity or a characterization of a yarn's ability to contractunder tension. When a textured yarn develops bulk, it shrinks, evenunder load. Crimp retention is relevant because it determines how muchself expanding the yarn can undergo. Especially in the blood wettedstate, this crimp retention parameter of the yarn determines how muchfiber is required to completely scaffold and, ultimately, durablyocclude a hollow anatomical structure.

Texturing methods are described in more detail by Peter R. Lord in thetextbook titled “Handbook of Yarn Production”, published in NorthAmerica by CRC Press LLC, 2000 Corporate Blvd, NW, Boca Raton, Fla.33431, USA in 2003, ISBN#0-8493-1781-9, which is hereby incorporated byreference herein in its entirety, and made a part of this specification.

One process for making a fibrous implant includes repeated stretching ofthe textured yarn to “unlock” the texture that has been associated withthe yarn. In some embodiments, no additional heating or cooling isrequired. The fibers are mechanically and repeatedly stretched.Stretching can be performed by hand and/or by machine. In the case ofyarns that have an air tack, this operation effectively removes the airtacks by untangling the tack. If the yarn does not have any air tacks,this operation still helps the spooled yarn regain its bulk sincespooling tends to collapse some of the bulk due to the tension requiredto spool the yarn. Additional details on manufacturing variousembodiments of the implant 10 and/or fibrous mass structure 12 arediscussed below, in the section tilted, “Manufacturing OcclusiveStructures.”

The long, continuous, thin fibers 14 of the fibrous mass structure 12can be scrunched, e.g., compressed along a longitudinal axis of thefibrous mass structure such that the cross-sectional width of thefibrous mass structure 12 is increased to occlude the hollow anatomicalstructure 20. In some embodiments, the fibrous mass structure 12 has theability to expand to several times the packed diameter upon exiting thedelivery sheath 16, thus potentially obviating the need for scrunching.For example, the fibrous mass structure 12 in one embodiment is packedinto a delivery sheath 16 having an inner diameter of about 2 mm. Whenthe fibrous mass structure 12 is deployed from the delivery sheath 16 itcan expand to fill a vein having a diameter of about 5 mm, or less, toabout 20 mm, or more. In some embodiments, when the fibrous massstructure 12 is deployed from the delivery sheath 16 it can expand tofill a vein having a diameter of about 4 mm, or less, to about 20 mm, ormore. In some embodiments, expansion of the fibrous mass 12 and hollowanatomical structure filling can rely on the fiber texturing, but mayalternatively use the twists and turns made by the fibers 14 as theybuckle during delivery so that subsequent delivery of the materialtightly packs and compresses the previously deposited material to more:completely fill the hollow anatomical structure 20.

As shown in FIG. 3, in some embodiments, a pull string 30 can be coupledwith the fibrous mass structure 12. In one embodiment, the pull string30 is coupled with a distal end 32 of the fibrous mass structure 12. Thepull string 30 can be actuated by the user or constrained withoutactuation and in combination with a proximal push sheath (not shown) tocause the fibrous mass structure 12 to “scrunch,” e.g., to shorten andthicken along the longitudinal axis, and expand radially, when deployedin the hollow anatomical structure, as will be described further below.In some embodiments, the pull string 30 can be automatically actuated.As shown in FIG. 4, in another embodiment, a pull string 30 is coupledwith a distal end 32 of the fibrous mass structure 12 and the pullstring 30 can be actuated by the user to fold the fibrous mass structure12, as will be described further below. As shown in FIG. 5, in oneembodiment, the pull string 30 is woven in and out of the fibrous massstructure 12 for better scrunch uniformity. Weaving the pull string 30through the fibrous mass structure 12 can produce “accordion-like”bending along the fibrous mass to improve the expansion characteristics,as will be described further below.

In some embodiments, the pull string 30 can be used to “scrunch” thefibrous mass structure against a distal portion of the delivery sheath16, or against the push rod 18. In some embodiments, the pull string 30,or an anchor string or tether string 40, can be used for retrieval orrepositioning of the implant 10.

An anchor string 40 can be coupled to the fibrous mass structure 12 topull or reposition the whole implant 10. The push rod 18 can also beused in some embodiments to push or reposition the whole implant 10 bypushing on the distal end and putting the implant 10 into tension. Thedistal portion of the delivery sheath 16 can also be used forrepositioning while constraining the pull string 30. The action ofrepositioning and/or moving the implant 10 within the hollow anatomicalstructure can improve occlusion by disturbing/denuding the endothelialcell lining in the hollow anatomical structure 20. Additionally, theanchor string 40 can be fixed at the access site acting as a fixationelement and/or anchoring mechanism to prevent the fibrous mass structure12 from migrating within the hollow anatomical structure 20. Othermechanical means associated with the fibrous mass structure 12 on itsdistal or proximal end or along the implant length can be contemplatedto secure the fibrous mass structure 12 to the hollow anatomicalstructure 20 for controlling implant migration including but not limitedto hooks, barbs, self-expanding radial structures, wish-bone shapedexpanding anchor wires, coil shaped hooks, radially expanding umbrellashapes, etc. Some or all of these can be made from non-bioresorbingand/or bioresorbing materials. Fibrous mass structure migration can alsobe controlled by first sealing/occluding the hollow anatomical structureusing RF energy, heating coil energy, laser energy, or surgicaltechniques like vessel ligation as well as external manual compressionof the hollow anatomical structure can be use to prevent acutemigration. Additional fixation techniques and structures are describedin more detail below.

In some embodiments, a balloon can be positioned within the fibrous massstructure 12. The balloon can be inflated to expand the fibrous massstructure 12 upon deployment. The balloon can then be deflated andwithdrawn, leaving the expanded fibrous mass structure 12 in place.Advantages of using a balloon include displacing or minimizing thenative fluid, such as blood present in the lumen, effectively stoppingthe blood flow thereby promoting the coagulation of the residual blood,preventing the implant 10 from migrating by anchoring the implant to thewall of the hollow anatomical structure 20. The balloon can also have alubricious coating so that the clot and/or implant 10 does not stick tothe balloon. Additionally, the balloon can also be made micro porouswhich can deliver sclerosant, thrombin, other bioactive agents to theimplant site.

In some embodiments, the implant 10 comprises, or is coupled with, amarker. The marker can be used for visualization of the implant 10. Themarker can be echogenic and/or radiopaque for visualization underultrasound, x-ray, or other visualization means. In some embodiments,other visualization methods and markers can be used. In someembodiments, a first marker is positioned on a first end of the fibrousmass structure 12, and a second marker is positioned on a second end ofthe fibrous mass structure 12. In some embodiments, the fibers 14 and/orthe fibrous mass structure 12 can incorporate trace metals includingpowdered tantalum, powdered tungsten, bismuth oxide, or barium sulfateto improve visualization. In some embodiments, the fiber composition canincorporate a physiologic/biologic marker which allows monitoring ofimplant 10 degradation byproducts as they transport during thedegradation cycle.

In some embodiments, a push rod 18 can be used to deliver, deploy orsecure the implant 10. In one embodiment, the push rod 18 is positionedwithin the fibrous mass structure 12 of the implant 10. In anotherembodiment, the push rod 18 is positioned proximal to the structure 12.In some embodiments, the push rod 18 engages the fibrous mass structure12 to hold it in place while the delivery sheath 16 is withdrawn. Aswill be described further below, the push rod 18 can be used to deliverthe fibrous mass structure 12 from the delivery sheath 16 into thehollow anatomical structure 20. In some embodiments, the fibrous massstructure 12 can be self-actuating. In other embodiments, the push rod16 and fibrous mass structure 12 can be configured to cooperate suchthat the user can actuate the fibrous mass structure 12 to the scrunchedconfiguration. In some embodiments the fibrous mass does not have anouter sheath. The fibrous mass is preferably placed using a push rod 16with an atraumatic tip. This embodiment has the advantage of minimizingthe time that the fibrous mass 12 is compressed within the sheath 16thereby improving the expansion characteristics of the implant 10.Furthermore, having no delivery sheath allows more fibers 14 to beplaced into the hollow anatomical structure 20 without the need toincrease the size of the access port.

Delivery Techniques

In one embodiment, a kit for treating a hollow anatomical structurecomprises a bioabsorbable fibrous implant 10, and a sheath 16 sized forinsertion into the hollow anatomical structure 20 having an innerdiameter configured to receive the implant 10 for delivery of theimplant into the hollow anatomical structure. A pushrod 18 is sized forinsertion into the sheath 16 and configured to advance the implant 10through the sheath 16 for delivery of the implant 10 into the hollowanatomical structure 20. According to some variations, the sheath 16comprises an abrasive element on its outer diameter. The abrasiveelement can be configured to engage a surface of the hollow anatomicalstructure 20 when the sheath 16 is inserted within the hollow anatomicalstructure 20. The kit can additionally comprise an implant lockingmechanism 50. The implant locking mechanism 50 can comprise a pullstring 30 configured to be coupled with the implant 10. The implantlocking mechanism 50 can comprise a funnel 52 coupled with the implant10. The pull string 30 can be knotted 54. The pull string 30 cancomprise a plurality of bumps 56 along at least a portion thereof.

In another embodiment, a method of treating a hollow anatomicalstructure 20 comprises delivering into the hollow anatomical structure20 an implant 10 comprising a plurality of loose tortuous fibers 14formed from one or more bioabsorbable materials. For example, accordingto one technique, a method of treating a hollow anatomical structure 20having a diameter of 4 mm or more comprises inserting into the hollowanatomical structure 20 a catheter having a size of 8 French or less. Abioabsorbable fibrous implant 10 is passed through the catheter and intothe hollow anatomical structure 20. With the implant 10, the patency ofthe hollow anatomical structure 20 can be reduced. In some embodiments,the method further comprises occluding the hollow anatomical structurewith the implant 10. The implant 10 can be expanded to a treatment statewithin the hollow anatomical structure 20 in some methods. The methodcan include promoting occlusive ingrowth with the implant 10 when theimplant 10 is in the hollow anatomical structure 20. The hollowanatomical structure 20 can comprise a vein. In some embodiments, thehollow anatomical structure 20 comprises a greater saphenous vein.Inserting the catheter can comprise inserting the catheter at aninsertion site spaced from the sapheno-femoral junction, and furthercomprise advancing the implant 10 from the insertion site to thesapheno-femoral junction. The hollow anatomical structure 20 can have adiameter of 4-12 mm in some embodiments. The hollow anatomical structure20 can have a diameter of 4-20 mm in some embodiments.

In another embodiment, a method of treating a vein comprises accessingthe vein at an access point spaced from a sapheno-femoral junction. Abioabsorbable fibrous body 12 is implanted into the vein through theaccess point. The body 12 is moved in the vein toward thesapheno-femoral junction. In some embodiments, the method additionallycomprises securing the body 12 in the hollow anatomical structure 20 tolimit migration of the body 12 within the vein. A sheath 16 can beinserted through the access point and the body 12 can be pushed with apushrod 18 through the sheath 16 into the vein in some methods. A heattreatment can be performed on the vein, and the heat treatment cancomprise one or more of delivering radio frequency energy, deliveringheat energy from a resistive element, and delivering energy from alaser. The method can additionally comprise moving an end of the body 12in the vein to the sapheno-femoral junction.

As shown in FIG. 6, according to one technique, an implant 10, e.g., afibrous mass structure 12, is provided. A delivery sheath 16 and a pushrod 18 are also provided. The implant 10 is loaded onto the push rod 18.The implant 10 is stretched and collapsed onto the push rod 18. The pushrod 18 is used to load the implant 10 into the delivery sheath 16. Oncea distal portion of the delivery sheath 16 has been positioned within ahollow anatomical structure 20, the push rod 18 is used to push theimplant 10 out of the delivery sheath 16 or, alternatively, the push rod18 is held still while the outer sheath 16 is retracted. The implant 10expands partially upon exiting the delivery sheath 16. The implant 10 isfurther expanded and scrunched as the delivery sheath 16 is pushedforward and the pull string 30 is pulled backward or held stillconstraining its movement.

According to one technique, ultrasound can be used to determine thediameter of the hollow anatomical structure 20 to be occluded. Thecompressibility of the hollow anatomical structure 20 can be determinedand a color-flow Doppler flow assessment can be performed. Anappropriate access site is selected. Local anesthetic can beadministered at the selected access site. An introducer sheath 16,cannula, or other access device can be positioned into an access vessel.In one embodiment, a 6 F sheath is used. In another embodiment, a 12 Gacannula can be used. Any suitable access device can be used.

A delivery device, e.g., a delivery catheter or sheath 16, is insertedinto the hollow anatomical structure 20 until a tip of the sheath ispositioned at a distal portion of the treatment segment. The fibrousmass structure 20 preferably is positioned within the delivery device aswill be described in more detail below. The location of the fibrous massstructure 12 preferably is verified using any suitable visualizationtechnique, e.g., ultrasound, x-ray. In some embodiments, a marker can bepositioned on the fibrous mass structure 12 such that it is clearlyvisible. The fibrous mass structure 12 is delivered into the hollowanatomical structure 20. If desired, the fibrous mass structure 12 canbe positioned or repositioned within the hollow anatomical structure 20under visualization. In some cases, it may be advantageous for one userto position the fibrous mass structure 12, while another usermanipulates the visualization equipment.

The fibrous mass structure 12 preferably is deployed to an expandedconfiguration. Any suitable deployment technique and/or expansiontechnique can be used. As shown in FIG. 3, in one embodiment, a pullstring 30 coupled to a distal portion 32 of the fibrous mass structure12 is pulled to scrunch the fibrous mass structure 12. Scrunching thefibrous mass structure 12 increases the density of the fibers 14 in agiven cross-section. As shown in FIG. 4, in another embodiment, a pullstring 30 coupled to a distal portion 32 of the fibrous mass structure12 is pulled to cause the fibrous mass structure 12 to fold over onitself. Folding the fibrous mass structure 12 increases the density offibers in a given cross-section. As shown in FIG. 5, in anotherembodiment, a pull string 30 is coupled to a distal portion 32 of thefibrous mass structure 12 and is woven through intermediate portions ofthe fibrous mass structure 12. Intertwining the pull string 30 with thefibrous mass structure 12 results in controlled scrunching of thefibrous mass structure 12 and increases the density of fibers 14 in agiven cross-section.

In some embodiments, the implant 10 is held in the scrunched position bya locking device 50. Any suitable locking device 50 can be used. In oneembodiment, the implant 10 comprises a ring locking mechanism 50. Asshown in FIG. 7, a stop 56 is positioned on the pull string 30. The pullstring 30 is coupled with the distal end 32 of the implant 10 and isthreaded through a relatively small funnel shaped portion 52 that iscoupled with a proximal portion 34 of the implant 10. The pull string 30is pulled through the funnel 52 with the delivery sheath 16 helping tohold the implant 10 (and thereby the funnel 52) still. The stop 56 ispulled through the funnel 52, but is sized large enough that it will notslide back through the funnel 52 in the opposite direction. Accordingly,the implant 10 is locked in the expanded scrunched configuration and thepush rod 18 and delivery sheath 16 are removed.

In another embodiment, the implant 10 comprises a knot locking mechanism50. As shown in FIG. 8, a knot 54 is loosely tied in the pull string 30around the push rod 18. The knot 54 is located near a proximal portion34 of the implant 10. The knot 54 is prevented from fully tighteningbefore the push rod 18 is withdrawn. The pull string 30 is coupled withthe distal end 32 of the implant 10. When the implant 10 is scrunched,the push rod 18 is removed and the knot 54 in the pull string 30 can betightened to keep the implant 10 scrunched. Accordingly, the implant 10is locked in the expanded scrunched configuration and the push rod 18and delivery sheath 16 are removed.

In another embodiment, the implant 10 comprises a ratchet lockingmechanism 50. As shown in FIG. 9A, a plurality of detents or stops 58,are positioned along the pull string 30. In one embodiment, the stops 58are similar to a cable-tie or zip-tie. The stops 58 can be positionedalong part, or all, of the pull string 30. The pull string 30 is coupledwith the distal end 32 of the implant 10 and is threaded through arelatively small funnel 52 shaped portion that is coupled with aproximal portion 34 of the implant 10. The pull string 30 is pulledthrough the funnel 52 with the delivery sheath 16 helping to hold theimplant 10 (and thereby the funnel 52) still. The stops 58 are pulledthrough the funnel 52, but they are too large to slide back through thefunnel 52 in the opposite direction. Accordingly, the implant 10 issufficiently scrunched and then locked in the expanded scrunchedconfiguration and the push rod 18 and delivery sheath 16 are removed.

After the implant 10 is delivered into the hollow anatomical structure20, the fibrous mass structure 12 can be positioned or repositionedwithin the hollow anatomical structure 20 under visualization. The pushrod 18 and anchor string 40 can be used to manipulate the implant 10.The delivery catheter can be withdrawn. The push rod 18 can bewithdrawn. External compression may be applied during removal of thepush rod 18 to help the implant 10 retain its position. The sheath 16can be withdrawn. External compression may be applied during removal ofthe sheath 16 to help the implant 10 retain its position.

In some techniques, the implant 10 is permitted to dwell for a timeperiod. The implant preferably is permitted to dwell for between about 1min, or less, to about 30 minutes, or more. In some techniques, externalcompression can be applied to force the walls of the hollow anatomicalstructure 20 to collapse and stick to the implant 10. In sometechniques, a vasoconstrictor can be applied to force the walls of ahollow anatomical structure 20 to collapse and stick to the implant 10.Following the dwell period, the position of the implant 10 is confirmedusing any suitable method. In some cases, the position of the implant 10is confirmed using a visualization technique, e.g., ultrasound, x-ray.In some cases, the position of the implant 10 is confirmed usingpalpation. Occlusion can be verified using any suitable method. Forexample, color-flow doppler can be used to evaluate or assess theocclusion.

As shown in FIG. 9B, according to another embodiment, an occludingdevice or implant 10 comprises a fibrous mass structure 12 and aninjectable gelatin 22 or any other occlusive materials (as listed above)deployed simultaneously or sequentially into the hollow anatomicalstructure. The two materials can either be intermingled, or remainseparated linearly along the hollow anatomical structure. The propertiesof the two materials are chosen and deployed in such a manner that theflowable material is prevented from migrating by the other material.

In some techniques, delivery of the implant 10 can be followed by aninjection of sclerosant, hydrogel, or another active agent 22 and/ordrug, as shown in FIG. 9B. Injection can be accomplished via use of amicro porous balloon catheter used to both deploy the fibrous mass 12and to inject an active agent 22. In some techniques, the implant 10 canbe pre-soaked in an active agent 22 in the operating room prior todelivery of the implant 10 to the treatment site. In some techniques,the implant is pre-soaked in an active agent 22 prior to packaging thedevice during manufacturing. In some embodiments, the implant 10comprises active agents 22 as an integrated part of the device. Theimplant 10 can comprise a coating or drug-eluting technologies thatfunction as an active agent 22. In some techniques, delivery of theimplant 10 can be followed or preceded by non-localized delivery of anactive agent 22. For example, the active agent 22 can be deliveredorally or as a topical paste.

Blood preferably collects and coagulates in and/or around the fibers 14of the implant 10. Initially, a thrombus is formed and preferablyorganizes as part of the foreign body natural healing process to createa fibrotic tissue occlusion. In some techniques, a growth factor can beused to promote fibrotic tissue growth. In some embodiments, a thrombincoating or seeding of the implant can initiate and promote thecoagulation cascade in order to increase tissue ingrowth. There are manyways to stimulate tissue ingrowth in a biodegradable polymer. One methodis to create a loose polymer scaffold (e.g., with any of the embodimentsof the implant 10 disclosed herein) and fill the interstitial space withhydrogel, e.g., fibrin gel. Fibrin gel induces tissue ingrowth. Tissuegrowth factor, e.g., fibroblast growth factor, can also be incorporatedinto the implant 10 with the hydrogel to promote tissue ingrowth. Inthis approach, the scaffold is delivered first, and then fibrinogen,thrombin, and/or growth factor solution is injected into the vein. Thesolution fills in the interstitial space and polymerizes to formhydrogel, which serves as a matrix for rapid tissue ingrowth. Analternative approach to the fibrin gel is to directly mix autogenousblood with thrombin and inject the mixed blood into the vein. Thiscreates a blood clot-like structure to fill the space and the clot'sproperty can be controlled by thrombin concentration. This is also agood matrix to induce tissue ingrowth and has advantages over un-aidednatural clotting. Another alternative, is to inject a fibrin or thrombinliquid rather than hydrogel into the sheath before the device isdeployed to soak the implant 10 prior to introduction. As well, theimplant 10 can be presoaked with this bioactive liquid and then dried aspart of the fabrication process prior to clinical use in a clinicalsetting, or as part of a manufacturing process. According to anothertechnique, a mix of autologus blood and fibrin is injected just beforethe device is deployed so that it envelops or soaks the implant 10 inthe outer sheath 16 before it is introduced into the hollow anatomicalstructure 20.

Additionally, there are other surface modifications or pretreatmentsthat can be made to the implant 10. The surface of the fiber(s) 14 ofthe implant 10, as well as the material polymeric chain itself, can bemodified or pretreated, e.g., charged, roughened, to be preferentiallyFibrinogen-philic over Albumin-philic. The first thing that happens,e.g., within the first 1-3 seconds after implantation, with anyhydrophobic implant material in the blood plasma stream is proteinadsorption on the surface. Just as immediately, Factor XIIa isactivated, starting the clotting cascade. If Albumin preferentially laysdown on the implant 10 it will tend to passivate the surface renderingit less reactive. Thus, it is advantageous to prevent or limit Albuminadsorption and to preferentially adsorb Fibrinogen onto the surface byadjusting the polymer, or surface of the polymer, charging the surface,or by hydrophobicity. In some embodiments, pre-absorption of Fibrinogenonto the implant 10 promotes a non-passivation. In some embodiments,making surface modifications can improve fibrotic occlusion, with orwithout adding Thrombin. By the intrinsic clotting cascade mechanism,Thrombin acts on the Fibrinogen (a reactive protein monomer circulatingin blood plasma, liquid) to become Fibrin monomers which are then crosslinked by Factor XIII to become Fibrin (a solid). This cross linkedFibrin is an organized thrombus (i.e., a fibrotic occlusion). Oneexample of this type of mechanism is Dacron (rough surface) which can beused on coils for occluding Berry Aneurysm's in the brain, as well asfor woven and knitted grafts. Dacron is nicely hydrophobic, as well. Itssurface preferentially adsorbs Fibrinogen over Albumin, quickly creatingFibrin and thus mural (wall) thrombus (all inside 10 minutes afterimplant) which helps to prevent endothelialization. However, silicones &polyurethanes are both very biocompatible and do not activate theclotting cascade as aggressively because they both adsorb Albumin morepreferentially than Fibrinogen.

Other mechanisms that improve performance include inhibiting the naturalfibrinolytic system in the region of the implant. As mentioned earlier,Factor XIIa starts the clotting cascade, but it also convertsplasminogen to plasmin. Plasmin is not desired because it is an enzymethat lyses a thrombus (e.g., a clot). By inhibiting the conversion ofplasminogen to plasmin, one can substantially prevent the naturaltendency toward lysation of the desired blood clot adjacent the implant.Plasmin is similar to Thrombin, except that Thrombin only cleavesfibrinogen to create fibrin monomers, which is desired. While Plasmincleaves both fibrinogen and fibrin creating fibrin split products (FSPs)or fibrin degradation products. These FSPs are preferably removed inorder to limit their inhibition of clot formation. These FSPs inhibitcross linking of the fibrin monomers by preventing them from contactingeach other so they can't create a fibrotic occlusion. For example,Tissue Plasminogen Activator (tPA) can be used for thrombolysis, as wellas other drugs like ReoPro (a GPIIb/IIIa inhibitor that basically bindsto human platelet IIb/IIIa receptors to prevent platelet aggregation).Therefore, drugs, surface coatings, and pre-treatments with bioactiveagents are preferably used or administered to do the opposite, i.e.,instead cause platelets to aggregate more aggressively and/oraggressively inhibit activation of plasminogin in the region of theimplant 10.

In some embodiments, bioactive agents that illicit the coagulationcascade to stabilize thrombus formation and promote a more durableforeign body response and fibrotic occlusion are desired. For example,in some embodiments, the implant 10 may be pre-treated with desirabletherapeutic and clinical agents such as growth factors, tissueattachment factors, clotting factors, chemotherapeutic agents,chemotactic factors, and anti-bacterial agents. These agents may becovalently bonded, ionically or hydrophobically bonded, coated,compounded, physically absorbed into the implant, or otherwise combinedwith the implant. Some bioactive agents include but are not limited to:antibiotics such as tobramycin, entamycin, and vancomycin; clottingfactors such as Factors I-VIII, thrombin, and fibrinogen; cytokines forexample basic fibroblast growth factor (bFGF), platelet derived growthfactor (PDGF), vascular endothelial growth factor (VEGF), transforminggrowth factor beta (TGF-β), TNFα, NGF, GM-CSF, IGFα, IL-1, IL-8, andIL-6; inflammatory microcrystals such as crystalline minerals andsilicates; tissue attachment factors such as fibronectin, laminin, andvitronectin; protease inhibitors such as aprotinin; extracellular matrixmolecules such as collagen and fibronectin; trace metals; irritants suchas trace amounts of talcum powder, metallic beryllium and silica; traceamounts of polymers such as polylysine and ethylenevinylacetate; otheradhesion inducing agents such as monocyte chemotactic protein,fibroblast stimulating factor I, histamine, endothelin-1, angiotensinII, bromocriptine, methylsergide, methotrexate, N-carboxybutyl chitosan,carbon tetrachloride, thioacetamide, quartz dust, fibrosin, and ethanol;or other molecules that stabilize thrombus formation or inhibit clotlysis for example proteins including Factor XIII, α2-antiplasmin,plasminogen activator inhibitor-1 (PAI-1) or the like; as well assclerosing agents such as morrhate sodium, ethanolamine oleate, andsodium tetradecyl sulfate and anti-bacterial/anti-infective agents orantibiotic drugs like amoxicillin; ampicillin; benzylpenicillin;chloramphenicol; clindamycin; erythromycin; lincomycin; rifampicin ormaterials like silver or silver ions, colloidal silver, silversulfadiazine, and/or silver nitrate.

The access site can be closed using any appropriate method, includingthrough use of a fibrous mass structure 12. In some cases, a steri-stripcan be used to close the access site. In some cases, the access site canbe closed with a suture. Compression bandages can be placed on thepatient. For example, where the surgical site is in a patient's leg,compression bandages can be positioned over the entire leg. Compressionbandages preferably are left in place for about three days according toone technique. After about three days, the site can be scanned for deepvein thrombosis and/or extension of thrombus from the superficial to thedeep system. The position of the implant is confirmed using avisualization technique, e.g., ultrasound, x-ray, or by palpation.Occlusion can be verified using any suitable method, e.g., color-flowDoppler, or contrast enhanced fluorographic x-ray.

Manufacturing Occlusive Structures

The fibrous mass structure 12 can comprise any suitable shape andconfiguration. In one embodiment, the fibrous mass structure 12 issimply a bundle of long, thin fibers 14. In another embodiment, as shownin FIG. 10, the fibrous mass structure 12 is a bundle of long thinfibers 14 coupled together at one end, generally resembling a tassel oran “octopus.” In another embodiment, the fibrous mass structure 12 is abundle of long thin fibers 14 coupled together at a first end and asecond end, as shown in FIGS. 2-9A. As shown in FIG. 11, in oneembodiment, long, thin fibers 14 can be arranged to form yarn that canbe processed into a tubular shaped structure, such as a sock. In someembodiments, the fibrous mass structure 12 can be coupled with anotherocclusive device. For example, as shown in FIG. 12, in one embodiment, abullet-shaped bioresorbable plug 70 can be coupled with a bundle oflong, thin fibers 14. In some embodiments, one or more of the fibers 14preferably has a fiber diameter of between about 5 microns, or less, toabout 30 microns, or more. In some embodiments, the fibers can havevarying outward axial dimensions. The plug 70 can be positioned within ahollow anatomical structure 20, and the plug 70 and fibers 14 canocclude the hollow anatomical structure 20.

As shown in FIG. 13, in some embodiments the implant 10 has aself-expanding element 80, e.g., a lattice, carcass, or coil, made fromthe same biodegradable material as the fibers 14 (or other biodegradablematerial) to hold the fibers 14 or strands more open to better fill thelumen space. The lattice, carcass, or coil structure 80 self expandsonce deployed in blood stream. The fibers 14 and the carcass 80 can becoupled at the proximal and/or distal end by any suitable couplingmechanism or, alternatively, coupled throughout the implant 10.Thrombin, fibrinogen, or other active proteins, peptides, and/or agents82, can be applied to surface of the fiber material 14 or combined intoan outer atomic layer of bioresorbable material to promote the surfaceto develop a fibrotic occlusion.

As described above, a self expanding internal element 80 can beprovided, in some embodiments. This self expanding internal element mayalso be made from a bioresorble material (e.g., a 0.010 inch, or less,to 0.012 inches, or more, monofilament). The self expanding internalelement 80 can comprise, e.g., a carcass, a cage, a coil, a stent body,a braid, and/or another suitable lattice structure. The element 80preferably is intertwined with a basic fibrous mass structure 12described herein. The element 80 can be provided to improve volumefilling to allow for treating larger vessels. The element 80 can improveimplant to vessel wall contact to provide more consistent and reliablebiologic occlusion. In some embodiments, the element 80 can be a shortsection coupled with a portion of the fibrous mass material 12. In otherembodiments, the element 80 can extend along approximately the fulllength of the implant 10. In some embodiments, the element 80 canprovide both anchoring properties and can reduce blood flow tofacilitate better biologic occlusion. In some embodiments, portions ofthe fibrous mass structure 12 spaced from the self expanding element 80can have a more loose texture, void content and scaffold which can allowfor some blood flow so that a pressure head is not developed which couldextend the vessel diameter and may lead to implant migration.

Any suitable method can be used for manufacturing an implant 10 having afibrous mass structure 12. Some methods for manufacturing the fibrousmass structure 12 can comprise one or more of knitting, weaving,felting, tangling, injection molding, heat forming, casting, spincasting, melt spun, electro spun, solvent casting, laser cutting,application of solvents, application of adhesives, extrusion, drawing,crimping, and other fiber processing techniques.

In one embodiment, the fibrous mass structure 12 can be formed byknitting fibers. In one embodiment a tubular fibrous mass structure 12is knit with a knitting fixture, e.g., knitting knobby, knitting nelly.The size of the knitting fixture can be selected to produce anappropriately sized tubular fibrous mass structure 12. Any suitablenumber of cables can be used. A knitting fixture having an appropriatenumber of pins can be selected based on the desired number of cablesneeded to achieve the desired thread count and the desired porosity ofthe finished weave. In one embodiment, the fibrous mass structure 12 canbe formed by weaving the fiber materials to form a tubular fibrous mass12. In another embodiment, the fibrous mass structure 12 can be formedby felting the fiber materials to form a dense non-woven mesh.Non-continuous or staple yarns can also be used to form the fibrous mass12. Carding, drawing, ring spinning, roving, general texturing by heatsetting the filaments into a crimped or convoluted form are used toprocess the fibers. It is also possible to mechanically lock the fibersor to tangle the fibers when heat setting has a detrimental effect onthe biodegradable material properties such as in air jet texturing.

A combination of staple and filament yarns can also be used to make thefibrous mass 12. An example of this involves wrapping of continuousfilaments around the staple fiber bundles or low twist staple yarns. Thestaple and filament yarns can be composed of different base materials.

According to one embodiment, fiber processing can comprise applying aspin finish to the materials to allow for a false twist texturing. Thefalse twist texturing can be used to bulk up the yarn. An S-twist can beapplied to the yarn. The yarn is heated in the twisted configuration.The yarn is preferably heated to between about 60 degrees C., or lessand about 150 degrees C., or more depending on the base material'sinherent transition temperatures. In other embodiments, temperaturesoutside of this range, and/or partially overlapping this range, can alsobe used. The yarn is then cooled and untwisted. Downstream annealing,detorquing, elongation reduction steps may be eliminated to enhance thetexturing of the implant. The material can also be heated, stretched andrelaxed several times to further bulk the yarn.

In another embodiment, the fibrous mass structure 12 can be formed byinjection molding. Materials can be heated above their melting pointsand injected into a space between a positive mold and a negative mold toform the fibrous mass structure 12. In some embodiments, the materialsare injected only into the negative mold. In another embodiment, thefibrous mass structure can be formed by heat forming. Materials can bepressed between a positive mold and a negative mold and heating belowthe melting point to retain the molded shape. In one embodiment, PLA,PGA, or other material yarn can be heat set into shapes while retainingthe original loft of the yarn.

In another embodiment, the fibrous mass structure 12 can be formed bycasting. For example, in one embodiment, gelatin, or another material,can be poured into tubes to form the fibrous mass structure 12. Inanother embodiment, the fibrous mass structure 12 can be formed by spincasting. In another embodiment, the fibrous mass structure 12 can beformed by solvent casting. For example, in one embodiment, a positivemold can be dipped into a solution to form the fibrous mass structure12. In another embodiment, a solution can be poured into a negative moldto form the fibrous mass structure 12. In another embodiment, a solutioncan be poured into the space between a negative mold and a positive moldto form the fibrous mass structure 12. In another embodiment, porousstructures or foam castings created during solvent casting can be madeby adding water dissolvable substances, e.g., salt, to the materialsduring casting and then dissolving the salt after curing. For example,solvent casting PLLA in methylene chloride or other solvent in thepresence of a porogen such as salt crystals. In another embodiment,porous structures can be made by adding ammonium bicarbonate to formgas-filled voids in the materials forming the fibrous mass structure 12.In another embodiment, solvent casting techniques can be used to createa fibrous mass structure 12. Fiber bonding is accomplished by immersingPGA fibers in a PLLA solution. When the solvent evaporates, the networkof PGA fibers is embedded in PLLA. Further heating allows the formationof a matrix of the two fibers. Methylene chloride or other solvent isthen used to dissolve the PLLA, leaving behind a PGA fibrous massstructure 12.

In some embodiments, secondary processing can include laser cutting,application of solvents, and/or application of adhesives to furtherdefine the fibrous mass structure 12. For example, in one embodiment,PLA and methylene chloride or other solvent can be used to prepare thefibrous mass structure 12.

Bioresorbable Materials

Suitable materials for forming fibers 14 and/or other components caninclude one or more biodegradable polymers. For example, suitablebiodegradable polymers can include alpha-hydroxy acids, such aspolyglycolides, polylactides, and copolymers of lactic acid and glycolicacid. Poly(lactic-glycolic acid) (PLGA) is a suitable material in someembodiments. PLGA is a synthetic absorbable copolymer of glycolide andlactide marketed under the trade name VICRYL™ (a Polyglactin 910manufactured by Ethicon, a division of Johnson & Johnson of Somerset,N.J.). It is absorbed though enzymatic degradation by hydrolysis.Polyglycolic acid (PGA) is a synthetic absorbable polymer. Polylactide(PLA) is prepared from the cyclic diester of lactic acid (lactide).Foams made from bioresorbable PLAs and/or PGAs are particularlypreferred.

The fibrous mass structure 12 preferably comprises fibers and/or othercomponents formed from one or more biodegradable polymers describedherein, and/or disclosed in U.S. Provisional Patent Application No.60/605843, filed Aug. 31, 2004, titled APPARATUS AND MATERIALCOMPOSITION FOR PERMANENT OCCLUSION OF A HOLLOW ANATOMICAL STRUCTURE; inU.S. Patent Applications Ser. No. 11/212,539, filed Aug. 26, 2005,titled APPARATUS AND MATERIAL COMPOSITION FOR PERMANENT OCCLUSION OF AHOLLOW ANATOMICAL STRUCTURE; Ser. No. 09/859,899, filed May 16, 2001,titled STENT GRAFTS WITH BIOACTIVE COATINGS; Ser. No. 09/861,182, filedMay 18, 2001, titled INJECTABLE DRUG DELIVERY SYSTEMS WITH CYCLODEXTRINEPOLYMER BASED HYDROGELS; and U.S. Pat. No. 4,938,763, issued Jul. 3,1990; U.S. Pat. No. 5,456,693, issued Oct. 10, 1995; U.S. Pat. No.6,423,085, issued Jul. 23, 2002; U.S. Pat. No. 6,676,971, issued Jan.13, 2004, and U.S. Pat. No. 6,699,272, issued Mar. 2, 2004, which areall hereby incorporated by reference herein in their entireties and madea part of this specification.

For example, in one embodiment, the fibrous mass structure 12 caninclude fibers 14 and/or other components formed from polylactidesand/or polyglycolides. As stated above, Polyglycolide (PGA) is asynthetic absorbable polymer. Polyglycolide, which exhibits hydrolyticsusceptibility, is typically absorbed within a few monthspost-implantation. Polylactide (PLA) and polyglycolide (PGA) areprepared from their cyclic diesters of lactide and/or glycolide by ringopening polymerization to synthesize higher molecular weight polymers orby direct polycondensation of lactic acid and/or glycolic acid tosynthesize lower molecular weight polymers. Lactic acid is a chiralmolecule existing in two optical isomers or enantiomers yielding threestereo configurations. The L-enantiomer is the biologic metabolite,while the D-enantiomer and a D,L racemic mixture results from thesynthetic preparation of lactic acid. The time required forpoly-L-lactide to be absorbed by the body is relatively long compared toother bioabsorbable materials especially when in the high molecularweight form. In some embodiments, the fibrous mass structure cancomprise fibers and/or other components formed fromepsilon-caprolactone, PEG, collagen, gelatin, starch,poly(acrylamide-co-hydrazide), and/or other bioresorbable materialsdescribed herein.

Many resorbable homopolymers and copolymers may be used for this deviceand include but are not limited to the following: polymers derived fromlactide, glycolide, and caprolactone which are common in clinical useand are characterized by degradation times ranging from days to yearsdepending on the formulation and initial Mw (Molecular Weight). Lacticacid is a chiral molecule, existing in L and D isomers (the L isomer isthe biological metabolite), and thus “polylactic acid” actually refersto a family of polymers: pure poly-L-lactic acid (L-PLA), purepoly-D-lactic acid (D-PLA), and poly-D,L-lactic acid (DL-PLA).Homopolymers of L-PLA as well as poly-caprolactone (PCL) have beenuseful clinically and are acceptable candidates. Additionally,polyglycolic acid (PGA), poly-glycolic/poly-L-lactic acid copolymers,poly(dioxanone), poly(trimethylene carbonate) copolymers, andpoly(hydroxybutyrate) (PHB) and copolymers of hydroxybutyrate withhydroxyvalerate as well as polyanhydrides, polyorthoesteres,polyphosphazenes, and others including natural biodegradables likecollagen, elastin, fibrinogen, fibrinectin, vitronectin, laminin,gelatin and lypholized small intestine submucosa and combinationsthereof are potential candidate material choices for this device.

In some embodiments, the degradation rate of the fibrous mass structurecan be selected by varying the ratio of bioresorbable materials withpre-determined individual degradation rates. For example, in oneembodiment, the fibrous mass structure comprises about 50% PGA and about50% PLA. In another embodiment, the fibrous mass structure comprisesabout 65% PGA and about 35% PLA. In another embodiment, the fibrous massstructure comprises about 70% PGA and about 30% PLA. In anotherembodiment, the fibrous mass structure comprises about 80% PGA and about30% PLA. In another embodiment, the fibrous mass structure comprisesabout 90% PGA and about 10% PLA. In another embodiment, the fibrous massstructure comprises about 100% PGA. In another embodiment, the fibrousmass structure comprises about 100% PLA.

The selection of the degradation period is based on maintaining adurable occlusion. The material degradation term preferably is chosen toensure durable fibrotic occlusion through tissue ingrowth, but not tooquickly that occlusion is unable to mature or that the materialembolizes before occlusion. As tissue grows in, the implant preferablyis going away. If the implant resides too long then there is potentialfor the patient to have a palpable cord along the leg.

In some embodiments, materials having molecular weights within a certainrange are chosen to achieve a certain degradation time. For example,materials can have a molecular weight of between about 1,000, or less,to about 100,000, or more Daltons, to produce a desired degradation timeperiod. Materials having intrinsic viscosities of between about 0.1dl/gm, or less, to about 4 dl/gm, or more, can affect the degradationrate and the ease of processing of the materials. In some embodiments,the degradation time period preferably is between about 2 weeks, orless, to about 2 years, or more. In some embodiments, one or more of thematerials can produce a desired inflammatory response within thepatient. In some embodiments, one or more of the materials can produce alocalized reaction, e.g., a pH change, as the material biodegrades.

In one embodiment, yarn fibers can be formed from one or more of thematerials described. In some embodiments, the fibrous mass structure 12can be between about 40 denier, or less, to about 7200 denier, or more.In some embodiments, the fibrous mass structure 12 can be between about200 denier, or less, to about 15000 denier, or more. A fibrous massstructure 12 can comprise between about 1 fiber to about 24 fibers, ormore, in some embodiments. A fibrous mass structure 12 can comprisebetween about 24 fibers to about 600 fibers, or more, in someembodiments. One or more of the fibers preferably has a fiber diameterof between about 5 micron, or less, to about 30 micron, or more, in someembodiments. In other embodiments, the fibers can be from 0.1 denier to10 denier and the implant can comprise between 500 and 100,000 fibers insome embodiments. In some embodiments, the implant can comprise between500 and 500,000 fibers. In some embodiments, the fibers can be from 5denier to 50 denier in some embodiments. In some embodiments, theimplant can comprise between 10 and 1,000 fibers in some embodiments.

In some embodiments, different copolymer fibers 14 can be mixed into alarger yarn for differential bio-degradation along the length of thefibrous mass structure 12. For example, in one embodiment, differentfibers 14 can be intertwined with the yarn near a front end of thefibrous mass structure 12 to act as a filter for the back end. Inanother embodiment, different fibers 14 can be intertwined with the yarnsuch that the fibrous mass structure 12 has different rates ofdegradation at different portions of the fibrous mass structure 12. Inone embodiment, for example, the fibrous mass structure 12 has differentrates of degradation throughout the cross section thereof to promotetissue ingrowth.

In one embodiments, as shown in FIG. 14, multiple materials can becombined to produce a fiber 14 having a customized degradation profile.The degradation rate of a particular fiber 14 can be different alongdifferent portions of the fiber. Additionally, the degradation rate ofthe implant 10 can be different along different portions of the implant10. In one embodiment, a particular fiber 14 has a first portion, forexample, along about 25% of the length of the fiber, having a relativelyslower degradation rate and a second portion, for example, along about75% of the length of the fiber, having a relatively faster degradationrate. In one embodiment, the first portion degrades more slowly that thesecond portion, so that the first portion acts like a plug to preventblood flow in the hollow anatomical structure 20. In another embodiment,the center-most fibers may be comprised of a different material than theouter-most fibers, thereby causing a differential absorption ratethrough the radial dimension. In some embodiments, multiple materialscan be coextruded to form fibers 14 having desired characteristics, asshown in the upper view of FIG. 14. In some embodiments, multiplematerials can be sequentially extruded to form fibers 14 having desiredcharacteristics, as shown in the middle view of FIG. 14. In someembodiments, multiple materials can be stranded together to form fibers14 having desired characteristics, as shown in the lower view of FIG.14.

In some embodiments, as shown in FIG. 15, fibers 14 can have variablecross sections to accelerate degradation while retaining a constantfiber outer diameter. Some variable thickness strands 14 comprise areaswith small cross-sections that degrade quickly, as shown in the upperview of FIG. 15. Some strands 14 having non-circular cross sections havean increased surface area to volume ratio to speed degradation, as shownin the middle and lower views of FIG. 15. Variable thickness strandsalso keep structures porous and open to provide scaffolding even whenmultiple fibers are positioned near each other. As shown in FIG. 16, insome embodiments there are no gaps between the strands 14 when packedtogether, while in other embodiments there are gaps between variablethickness strands 14 even when they are packed together. Additionally,as shown in FIG. 17, in some embodiments hollow fibers 14 are used.Hollow fibers 14 wick blood into the fiber, allowing for more surfacearea contact leading to faster degradation. Additionally, perforationsalong the length of the fiber 14 can be used in some embodiments,especially if the desired fiber length is longer than the distance thatblood can travel by capillary action alone.

In some embodiments an implant 10 can comprise a multi-material yarn. Inone embodiment, a bicomponent fiber can be used. Some U.S. bicomponentfiber producers include: BASF Corporation; DuPont Company; FiberInnovation Technology, Inc.; KoSa; and Solutia Inc. A bicomponent fiberis comprised of two polymers of different chemical and/or physicalproperties extruded from the same spinneret with both polymers withinthe same filament or fiber. Some advantages, capabilities, andproperties of bicomponent fibers include: thermal bonding; self bulking;very fine fibers; unique cross-sections; and the functionality ofspecial polymers or additives at reduced cost. Most commerciallyavailable bicomponent fibers are configured in a sheath/core,side-by-side, or eccentric sheath/core arrangement. Bicomponent fiberscan advantageously provide for variable degradation rates of a fibrousmass structure 12. Self bulking bicomponent fibers are created mostoften with side-by-side or eccentric cross sections. The variation inorientation across the fiber causes crimping due to differentialshrinkage or strain with applied heat or relaxation.

Continuous Feed Delivery Systems

In some embodiments, a system for treating a hollow anatomical structurecomprises a bioabsorbable fibrous implant (such as one or more of theembodiments shown in FIGS. 2-13) sized for insertion into the hollowanatomical structure. A continuous feed mechanism can be configured oremployed to deliver the implant into the hollow anatomical structure.

FIGS. 18-23 illustrate embodiments of continuous feed hollow anatomicalstructure occlusion systems 200. The embodiments of FIGS. 18-23generally involve structures capable of continuously delivering sectionsof a fibrous mass structure 210 into a hollow anatomical structure 220,thereby allowing substantially larger veins and/or longer sections of ahollow anatomical structure to be occluded with a fibrous mass structure210.

The fibrous mass structure 210 used in connection with a continuous feedhollow anatomical structure occlusion system can include any suitablefibrous occlusive structure, such as those described elsewhere herein.For example, the fibrous mass structure can comprise a plurality offibers of bioresorbable or other materials. In some embodiments, thefibers can be loosely arranged such that they can be “scrunched” to formmasses of higher density fibrous structures. In alternative embodiments,the fibrous mass structure may include a plurality of knots or otherrelatively high density masses positioned at intervals along theelongate structure. In some embodiments, the elongate fibrous massstructure can have an un-compressed length that is longer than adelivery device. For example, in some embodiments the fibrous massstructure can have an un-compressed length between about 1 m and about30 m, and in one particular embodiment, the fibrous mass structure hasan un-compressed length of about 3 m. In an implanted state, a fibrousmass structure is typically compressed to occupy a substantially shorterlength and smaller volume than in a loose uncompressed state.Post-implantation the fibrous mass structure can have a compressedlength within the hollow anatomical structure between about 5 cm or lessto about 30 cm or more, in some embodiments from 10 cm or less to 20 cmor more.

FIGS. 18-23 illustrate embodiments of a continuous feed hollowanatomical structure occlusion system comprising a continuous length ofa fibrous mass 210 and an axially reciprocating delivery member 230within an outer sheath 232. The axially reciprocating member 230 isgenerally configured to eject portions of the fibrous mass 210 from thedistal end 240 of the outer sheath 232. The axially reciprocating member230 is generally configured to engage the fibrous mass 210 as thereciprocating member 230 moves in the distal direction relative to theouter sheath 232, thereby ejecting a segment of the elongate fibrousmass 210 out the distal end 240 of the sheath 232. In some embodiments,the axially reciprocating member 230 is further configured to disengagethe fibrous mass structure 210 as the member 230 moves in the proximaldirection, thereby allowing the reciprocating member 230 to moveproximally relative to the sheath 232 and fibrous mass 210 withoutpulling the fibrous mass 210 proximally.

In one embodiment, illustrated for example in FIGS. 18-20, thereciprocating member 230 comprises an elongate push rod positionedwithin the outer sheath 232 and alongside the elongate fibrous massstructure 210. The reciprocating member 230 of this embodiment cancomprise a distal pusher head 242 that is movable between a firstposition in which the head 242 engages the fibrous mass 210, and asecond position in which the head 242 disengages the fibrous mass 210during proximal movement of the push rod 230.

In the embodiment of FIGS. 18-20, the push rod comprises a material andconstruction with a sufficient column strength to transfer an axialforce applied at the proximal end of the rod to the fibrous massstructure 210 via the pusher head 242 at the distal end of the rod. Thepush rod is also preferably sufficiently flexible to allow the entiredevice to be navigated through a patient's vasculature to a desireddelivery site.

In the embodiment illustrated in FIG. 21, the pusher head 242 comprisesa pair of hinged legs 244 configured to pivot between a first (open)position, and a second (closed) position. In one embodiment, the legs244 are biased outwards by a spring or other resilient biasing member.In such an embodiment, the biasing force is preferably sufficientlysmall that the legs deflect towards the second position as the push rodis pulled proximally relative to the fibrous mass structure 210. In analternative embodiment, the legs 244 can be manually moved between thefirst and second positions by an actuation member, such as a pull and/orpush wire.

In another embodiment, a pusher head can include a plurality of legsmade of a rigid, resilient material. The legs can be biased radiallyoutwards toward a first, expanded position in which the legs engage theelongate fibrous mass structure. The legs can further include asufficiently small biasing force that they disengage the fibrous massstructure as the rod is pulled proximally. In still another embodiment,a pusher head can be provided with a single radially expandable andcontractible member configured to engage the fibrous mass structure ondistal movement of the reciprocating member. And in still anotherembodiment, a pusher head can be made of a rigid material. The legs canbe fork or “V” shaped to engage the fibers as the fork is pushed forwardto deliver the fibrous mass structure and does not engage the fibers asthe fork is pulled relative to the delivered fibrous mass structure. Amultitude of pusher head shapes can be envisioned and are within thescope of this invention.

FIGS. 21-23 illustrate alternative embodiments of a continuous-feedhollow anatomical structure occlusion system. In the embodiments ofFIGS. 21-23, the axially-reciprocating member 230 comprises an internallumen 250 through which the elongate fibrous mass structure 210 extends.The axially reciprocating members 230 of these embodiments alsopreferably include distal pusher heads 242 configured to push thefibrous mass structure 210 distally as the reciprocating member 230 ismoved distally relative to the outer sheath 230. As in the previousembodiments, the pusher heads 230 are preferably configured to disengagethe fibrous mass structure 210 as the head 230 is moved proximallyrelative to the outer sheath 232 and the fibrous mass structure.

In the embodiment of FIG. 21, the pusher head 230 comprises a pair ofhinged gripper members 252. In alternative embodiments, a pusher headmay comprise anywhere from one to four or more gripper members. Each ofthe gripper members 252 is resiliently biased inward in order to pinchthe fibrous mass structure extending between the grippers 252. Thegripper members 252 are preferably configured such that the frictionbetween the gripper members 252 and the elongate fibrous structure 210is sufficient to cause the gripper members 252 to pivot inwards, therebygripping the fibrous structure 210 on distal movement of thereciprocating member 230. The gripper members 252 are also preferablyconfigured to disengage the fibrous structure 210 on proximal movementof the reciprocating member 230. These characteristics can be achievedby providing teeth on the gripper members 252 or by varying a lengthand/or bias force of the gripping members 252.

The embodiment of FIGS. 22 and 23 comprises a pusher head 230 having aplurality of claws 260 extending from the distal end of an inner sheath262. The claws 260 are generally biased radially inwards such that theywill pinch the fibrous mass, particularly during movement of the innersheath 262 in the distal direction. The claws 260 can be formed bycutting a cylindrical section of tubing to form pointed segments. Theclaws 260 can then be bent inwards in order to engage the fibrous mass210. In alternative embodiments, the distal section of the inner sheathcan include a section of reducing diameter, such as a conically shapedsection with a distal opening sized to allow a fibrous mass to be pulledtherethrough in the distal direction, but preventing the fibrous massfrom being pushed proximally into the distal opening. In otherembodiments, the outer sheath 232 can also comprise the plurality ofclaws 260 extending from the distal end of the outer sheath 232 oralternatively may be comprised of a resilient polymeric material of coneshape and reduced diameter at its distal end, a heat formed polymericduck-bill shape, or machined metallic claw feature. A multitude ofalternative embodiments can be envisioned and are within the scope ofthis invention.

The embodiment of FIGS. 24-26 comprises a reciprocating member 230 witha rigid fork shaped pusher head 242 used to deliver the fibrous massstructure 210. The pusher head 242 engages the distal end of the fibrousmass structure 210 and forces it past the claws 260 on the outer sheath232 as shown in FIG. 25. This interaction preferentially delivers aportion of the fibrous mass structure into the hollow anatomicalstructure. The reciprocating member 230 is then retracted and disengagesfrom the fibrous mass structure 210. In this embodiment, any reversemovement of the fibrous mass structure 210 back into the outer sheath232 is prevented by the claws 260. This action also allows the pusherhead 242 to fully disengage from the fibrous mass structure 210 as it isdelivered as shown in FIG. 26. The reciprocating member 230 is againactuated forward, the pusher head 242 again engages the fibrous massstructure 210 in a different location along its length and delivers morefibrous mass structure 210 out the outer sheath 232 and into the hollowanatomical structure. This cycle is repeated continuously until thedesired quantity of fibrous mass structure is delivered or the desiredtreatment length is achieved.

In some embodiments, it is desirable to temporarily hold the fibrousmass 210 substantially stationary in order to prevent the axiallyreciprocating member 230 from pulling the fibrous mass proximally duringproximal movement of the axially reciprocating member 230. In someembodiments, the fibrous mass may be held against movement in theproximal direction by simply abutting the distal edge of the outersheath after having been ejected from the sheath 232 as shown in FIG.19. In alternative embodiments, the outer sheath can include a pluralityof claws or a section of reducing diameter or other structures similarto the pusher heads described above.

In some embodiments, it is desirable to associate the reciprocatingmember 230 and the outer sheath 232 with an automated or manual pistolgrip handle allowing for single handed, easy and continuous delivery ofthe fibrous mass structure 210 as shown if FIG. 27 a-27 c. As shown inFIG. 27 c, first, a push rod is used to get the implant materialstarted. Then the handle is actuated to engage and advance the implantmaterial. Then the handle is released leaving the implant materialdispensed into the hollow anatomical structure. Then, the handle isactuated again, packing more implant material into the same location.Then, the handle is released only partially. If the friction between theimplant material already deployed and the hollow anatomical structurewall is sufficient, additional material will be deposited. Manualcompression may also be used to keep the implant material from goingbackward with the handle. Then, the handle is actuated again, andimplant material is deposited along the vein tract. This can be repeateduntil desired treatment length is filled.

In an additional embodiment, for fibrous mass structures 210 longer thanthe outer sheath 232, the fibrous mass structure 210 may be coiled ontoa spool 250 or contained in a cartridge (not shown) and configured tofeed off the spool 250 or cartridge into the proximal end of the outersheath 232 as the distal end of the fibrous mass structure 210 iscontinuously advanced into the hollow anatomical structure as shown inFIG. 28.

In an alternative embodiment, the fibrous mass can be deployed into thevessel using a small volume stream of compressed gas (e.g. CO2) to ejectthe material into vessel, thereby obviating the need for a push rod.

In another embodiment, the fibrous mass structure 210 can be introducedin a long overlapping manner rather than short packed segments. In suchembodiments, the fibrous mass structure 210 is delivered along theentire treatment length while the entire catheter assembly is retracted.The entire catheter assembly is then advanced forward and anothersegment of fibrous mass structure 210 is delivered along the entiretreatment length. This cycle can be repeated to deliver the fibrous massstructure 210 over a long treatment length. One embodiment of such anover-lapping deployment system is shown in FIG. 29.

As shown in FIG. 30, in still another embodiment, the outside of theouter sheath 232 can also include a scraping portion 280 at the distalend extending a length of 2 cm or less to 10 cm or more that acts tobrush and scrape the intimal lining of the vessel as the catheter isadvanced to the treatment site. This effectively denudes and disruptsthe endothelial cells lining the vessel as well as the internal elasticlamina within the intima of the vessel. This combination allows forsimultaneous denudation of the intimal lining of the vessel as thecatheter carrying the fibrous mass structure 210 is advanced to thetreatment site, obviating any need for an additional separate step toinjure the intima of the vessel prior to deploying the fibrous massstructure. Disrupting the intimal structure of the vessel allows for amore durable occlusion by allowing for improved tissue in-growth andintegration of the fibrous mass structure to the vessel wall during thecoagulation cascade and body healing process. Alternatives forimplementing the scraping portion 280 include but are not limited to:bristle brush elements extending from the catheter; a simple scuffedsurface formed by, e.g., beadblasting; an etched surface; micromachinedminiature cutting blades; a polymeric raised flap; specially designedand separate machined component associated with the outer sheathsurface, etc.

As shown in FIG. 31, in some embodiments, an abrasive surface can beprovided on a sheath, a catheter, a tool, a scraper and/or an implant toengage a surface of a hollow anatomical structure. In some embodiments,the abrasive surface can comprise a brush and/or a rasp. According toone technique, during delivery of an implant, the surface of a hollowanatomical structure can be engaged by the abrasive surface forendothelial denudation to set up better biologic occlusion. For example,a brush like component could be attached to the outer surface of thedelivery system or a separate brush can be used prior to implantdelivery. The purpose of the brush is denuding the endothelial cellsthat line the lumen and disrupting vessel internal elastic lamina. Bothactions improve tissue in-growth and fixation in the chronic phase. Thebrush material can be left in place as an occluder in some embodiments.The brush can be made out of bioabsorbable materials or fromnon-absorbable materials. As shown in FIG. 31, in some embodiments, theabrasive surface can comprise one or more of a fishbone configuration290, a propeller configuration 292, a zig-zag configuration 294, asponge and/or foam brush configuration 296, and one or more bristlesconfigured to wrap around a shaft in a secondary spiral shape 298.

Termination and Fixation

With reference to FIGS. 32-57C, according to some embodiments, anapparatus 300 for treating a hollow anatomical structure 320 comprises abioabsorbable fibrous body 312. A fixation member 302 is associated withthe body 312 and configured to limit migration of the body 312 whenimplanted in the hollow anatomical structure 320. According to oneaspect of the embodiments, the fixation member 302 comprises a tether340. According to another aspect of the embodiments, the fixation member302 comprises an anchor 360. According to another aspect of theembodiments, the fixation member comprises an expandable element 380.According to another aspect of the embodiments, the fixation membercomprises a braid 382. These and other embodiments, methods, techniquesand aspects are described further herein.

In some embodiments, implants 310 are configured to be securelypositioned within a hollow anatomical structure 320. Fixation within ahollow anatomical structure 320 can reduce the likelihood of implantmigration. Several fixation techniques and structures are described inmore detail below. Other suitable fixation techniques and structures canalso be used to limit implant migration. In one embodiment, abioresorbable occlusive scaffold implant 310 is configured for deliverythrough a catheter, e.g., an 8 F catheter. In some embodiments, thebioresorbable occlusive scaffold implant 310 is preferably supplied in alength long enough to provide sufficient material to treat the hollowanatomical structure 320 along the entire desired implantation lengthand to allow for excess material of the scaffold implant to be trimmedaway. According to one fixation technique described further below, thescaffold implant 310 can be cut off at the skin surface near the accesssite 304. A portion of the scaffold implant 310 can be tucked under theskin if desired. In some embodiments, a tether 340 preferably is coupledwith the scaffold implant 310 at a distal portion of the scaffold 310.The tether 340 preferably extends through the access site 304 and issecured to the patient's skin near the access site 304.

Fixation Methods

According to one technique, a method of treating a hollow anatomicalstructure comprises implanting a bioabsorbable fibrous body 312 in ahollow anatomical structure 320 and securing the body 312 in the hollowanatomical structure 320 to limit migration of the body 312 within thehollow anatomical structure 320. According to one aspect of thetechnique, securing the body 312 comprises anchoring the body 312 at anaccess site 304 of the hollow anatomical structure 320. According toanother aspect of the technique, securing the body 312 comprisesimplanting an expandable anchor 380 near the body 312 in the hollowanatomical structure 320. According to another aspect of the technique,securing the body 312 comprises thermally shrinking the hollowanatomical structure 320 near an implant location in the hollowanatomical structure 320. Implanting the body 312 preferably comprisesimplanting the body at the implant location. According to another aspectof the technique, securing the body 312 comprises securing the body 312with a fenestration anchor 360. According to another aspect of thetechnique, securing the body 312 comprises anchoring the body at apercutaneous retrograde access site 306. These and additional aspects,techniques, methods, and embodiments are described in more detail below.

Access Site Anchor

As stated above and as shown in FIGS. 32-36 and 37B, according to oneaspect of the technique, securing the body 312 comprises anchoring thebody 312 at an access site 304 of the hollow anatomical structure 320.According to another aspect of the technique, the method furthercomprises positioning the body 312 so that a portion of the body 312extends out of the hollow anatomical structure 320 through the skin ofthe patient at an access site 304 on the skin, as shown in FIG. 33.According to another aspect of the technique, the body further comprisesa tether 340, and the method further comprises trimming an end portionof the body 312 so that it is substantially flush with the skin and sothat the tether 340 extends beyond the body 312 through the access site304, as shown in FIG. 34. According to another aspect of the technique,the method further comprises securing the tether 340 near the accesssite 304, as shown in FIG. 35. These and other aspects, techniques,methods and embodiments are described further herein.

The hollow anatomical structure to be treated is preferably accessed ata site proximal to the segment to be treated using the Seldingertechnique. An introducer sheath (preferably sized from 6 F to 8 F) isinserted at the site for use during implant delivery. According to thisaspect, the implant 310 is coupled to the vein 320 at the access site304. Several methods and structures for coupling the body 312 to thehollow anatomical structure 320 at the access site 304 are describedherein.

According to one embodiment, a bioabsorbable full length fibrous massstructure 312 is configured to extend from near the sapheno-femoraljunction through the vessel, across the access site 304, and terminateoutside the body. An anchor string and/or tether 340 can run from adistal portion of the implant 310 proximally through a generally centralportion of the implant 310 and can extend through the access site 304and terminate outside the body when the implant 310 is positioned withina hollow anatomical structure 320 of the body. In some embodiments, theimplant 310 itself preferably comprises any of the combinationsdisclosed herein. As described above, the fiber processing parameterspreferably are selected to maximize fiber crimp retention which enhancesthe self expanding and/or volume filling properties of the implant 310.As described above, the implant 310 can be pre-folded over the tip of apushrod and in some cases can be manually textured to entangle andcreate further bulk if necessary and/or desired. Termination outside thebody can be performed by one or more active fixation techniquesdescribed herein or other suitable techniques to limit implantmigration.

In some embodiments, an implant 310 comprises a tether string 340. Thestring 340 preferably is a multifilament string or a monofilament of athicker cross section than the remainder of the implant, or braidedsuture material. In one embodiment, a first end portion of the string340 is attached at a proximal end portion of the implant 310. In someembodiments, the string 340 is attached to the implant 310 at the distalend portion of the implant 310, and/or at a plurality of locations onthe implant 310. A second end portion of the string 340 preferably isattached to the body tissue at the access site 304. According to onemethod of attachment, a knot is tied in the string 340 outside the wallof the hollow anatomical structure 320, as will be described in moredetail below. The bulk of the knot preferably prevents the string 340from sliding back though the wall of the hollow anatomical structure320. For example, a knot, e.g., an overhand knot, can be tied in thefree end of the tether string 340 to anchor the implant 310 at theaccess site 304. A blunt tool can be used to ensure that the knottightens close to the exit point from the skin. Multiple knots can beformed. The end of the tether string 340 can be threaded into the tip ofa knot pusher and/or a blunt cannula. The end of the string 340 can bepre-stiffened with cyanoacrylate to make threading the tether stringeasier. In some embodiments, Loctite 4061 can be used to pre-stiffen thetether string 340. A tether string 340 comprising a monofilament suturemay or may not require stiffening in some embodiments. The knot pusheris advanced to the knot and then used to push the knot below the surfaceof the skin. The knot pusher is then removed. Accordingly, the knot ispositioned outside the wall of the hollow anatomical structure 320, butbelow the skin surface. Excess tether string can be cut off just belowthe skin surface. Additional wound closure techniques can be used at theincision site, e.g., steri-strips and/or tissue adhesives.

According to another method of attachment, the string 340 can terminatein a needle 342, as shown in FIG. 38, or be coupled with a needle, e.g.,threaded through a separate needle, and then tied or sutured to thesubcutaneous tissue or to the skin. The knot can reside in thesubcutaneous tissue outside the hollow anatomical structure 320 andabsorb into the tissue over time. In some embodiments, the string 340can be made of the same material as the implant 310. It is possible toattach a monofilament, braided, and/or multifilament string 340 at anyone or more locations along the length of the implant 310, as shown inFIG. 39. According to some embodiments, coupling the tether string 340to multiple locations along the length of the implant 310 can facilitateanchoring the implant 310 in a desired location and can also preventmovement of the implant 310 at an end of the implant 310 opposite theanchor site. By coupling the tether string 340 at multiple locations,the implant 310 may be less likely to change dimensions. In someembodiments, the string material can also comprise one or morebioabsorbable materials that degrade more slowly than the implant 310.Additionally, the geometry and/or configuration of the string 340 caninfluence its degradation rate. For example, a string 340 made of thesame material as the implant 310 may nonetheless degrade more slowly ifthe diameter of the fibers in the string 340 are significantly largerthan the diameter of the fibers 314 that form the implant 310.

In some embodiments, the implant 310 itself can form the anchor. Atleast a portion of the implant 310 can exit the hollow anatomicalstructure 320 at the access site 304 and can be left in the subcutaneoustissue and/or positioned across the skin. According to another aspect ofthe technique, the method further comprises positioning the body 312 sothat a portion of the body 312 extends out of the hollow anatomicalstructure through the skin of the patient at an access site 304 on theskin. According to another aspect of the technique, the body furthercomprises a tether 340, and the method further comprises trimming an endportion of the body 312 so that it is substantially flush with the skinand so that the tether 340 extends beyond the body through the accesssite 304. According to another aspect of the technique, the methodfurther comprises securing the tether 340 near the access site 304.Alternatively, in some embodiments, both the tether string and thefibrous mass are cut flush to skin and/or tucked under the skin, suchthat nothing extens through the skin of the patient at the incision.

In some embodiments, a bioabsorbable tab 350 is provided. Thebioabsorbable tab 350 preferably is a separate component. It ispreferably deployed on the outside of the hollow anatomical structure320 in the subcutaneous tissue. The bioabsorbable tab 350 preferably isconnected to the implant 310 via a tether string 340 that crosses thewall of the hollow anatomical structure 320. Alternatively, thebioabsorbable tab 350 may be connected directly to the implant 310. Forexample, at least a portion of the implant 310 can comprise and/or becoupled with a bioabsorbable tab 350. At least the portion of theimplant 310 with the tab 350 can extend through the access site 304 suchthat the bioabsorbable tab 350 can be coupled to the subcutaneoustissue. In some embodiment, the tab 350 can have dimensions of about 1mm×2 mm×10 mm. In other embodiments, the tab 350 can be smaller orlarger. The tab 350 can be made out of PLA, 50/50 PLGA, and/or otherbioabsorbable polymers, e.g., some bioabsorbable polymers may beparticularly suitable for injection molding. The tab 350 preferably hasa geometry and dimensions such that it can be deployed through the samedelivery sheath as the implant 310 (e.g., 8 F). The tether string 340preferably comprises a flexible (suture-like) material. In someembodiments, the tether string 340 can be a monofilament ormultifilament braided and/or multifilament yarn. In some embodimentscomprising a tether string 340, a first portion of the tether string 340is preferably coupled to the bioabsorbable tab 350 and a second portionof the tether string 340 is preferably coupled to the implant 310. Theattachment at the implant 310 can be on the distal or proximal portionsof the implant 310 or in a middle portion, or at any combination oflocations. The tether string 340 can control how much the implant 310 isable to stretch when implanted in a hollow anatomical structure 320. Asshown in FIG. 39 the tether string 340 can be coupled at a proximalportion of the implant 310, at a plurality of locations on the implant310, and/or at a distal portion of the implant 310 with one or moreknots 344. Additionally, the tether string 340, in some embodiments canbe coupled only at a middle and/or intermediate portion of the implant.FIG. 39 also shows a portion of the tether string 340 coupled with a tab350. In some other embodiments, the tether string 340 can be coupledwith another type of anchor and or coupled directly with a portion ofthe patient's anatomy, e.g., as described herein. Fastening the tether340 to the distal end portion of the implant 310 effectively fixes thatend portion of the implant 310 relative to the access site 304. Thetether string 340 can be attached to the tab 350 in any suitable manner.In some embodiments, the tether 340 is coupled to the tab 350 using oneor more of a bioabsorbable cyanoacrylate adhesive, a thermal bondingtechnique, and a mechanical connection, e.g., a knot tied in the tether340 can prevent it from sliding through a hole in the tab 350 as shownin FIG. 37B.

FIGS. 36A-F illustrate several techniques for fixing the implant 310relative to the access site 304, for some of the embodiments which havebeen described above. FIG. 36A illustrates a fixation procedure whereinthe implant 310 is cut generally flush with the patient's skin and thetether string 340 is cut off about 5 cm (2 inches) beyond the skin. Thewound is preferably closed with a steri-stip, Tegaderm™, or othersuitable wound closure element. The tether 340 is then taped to the skinof the patient. The tape can be removed after several days and thetether is cut flush with the skin. FIG. 36B illustrates a fixationprocedure wherein the implant 310 and the tether 340 extend across thewall of the hollow anatomical structure 320 and are both cut generallyflush with the patient's skin. The wound is closed and the implant 310and tether 340 are held within the subcutaneous tissue. FIG. 36Cillustrates a fixation procedure wherein the implant 310 is cutgenerally flush with the patient's skin and a bioabsorbable tab 350 isattached to the tether string 340. The tab 350 is coupled to thesubcutaneous tissue under the skin to anchor the implant 310 and thewound is closed. According to one technique, the anchor tab 350 isthreaded onto the free end of the tether string 340 and the tetherstring 340 is knotted close to the exit point from the skin to act as astopper knot to retain the anchor tab 350. One end of the anchor 350 isinserted into the incision. A cannula or blunt tool can be used to pushthe anchor 350 below the skin surface. Accordingly, the anchor 350 canbe positioned outside the vein, but below the skin surface. Additionalwound closure techniques can be used at the incision site, e.g.,steri-strips and/or tissue adhesives. FIG. 36D illustrates a fixationprocedure wherein the tether string 340 attached to a needle 342. Thewound is closed and the tether 340 is stitched into the tissue to anchorthe implant 310. FIG. 36E illustrates a fixation procedure wherein thetether string 340 is cut off about 5 cm (2 inches) beyond the skin. Thetether is then tucked under the skin and the wound is closed. FIG. 36Fillustrates a fixation procedure wherein the implant 310 is stretched,cut, and allowed to slide back towards the hollow anatomical structure320 to minimize expansion of the incision. The anchor string 340 exitsthe incision and is coupled, e.g., taped, to the skin. The implantthickness preferably does not dilate the incision. The anchor string 340preferably is low-profile to allow the incision to fully close uponprocedure completion. Variations and combinations of the techniques ofFIGS. 36A-36F can also be used.

Advantages of some embodiments and techniques using an access siteanchor include the ability to mechanically couple the implant with awall of the hollow anatomical structure and/or surrounding tissue. Theprocedure is relatively easy and fast and no additional anesthesia isrequired.

Expandable Anchor

As stated above and as shown in FIG. 37C, according to another aspect ofthe technique, securing the body 312 comprises implanting an expandableanchor 380 near the body 312 in the hollow anatomical structure 320. Forexample, in one embodiment, an expandable structure 380, e.g., a braid382, can be deployed through a catheter and expanded in a vein near thesapheno-femoral junction as shown in FIG. 37C. The structure 380preferably has sufficient radial force to engage the vein wall andanchor the implant 310 in place. The proximal end portion of the implant310 preferably is coupled to the braid 382. The braid 382 can comprisebioabsorbable materials. In some embodiments, monofilaments arepreferred for forming the braid 382, due to their higher flexuralmodulus compared to multifilament braids or multifilament yarns.However, multifilament braids or multifilament yarns could be used insome embodiments. Monofilament fibers can provide increased radialstrength. In some embodiments, the braid 382, when deployed, is about 2cm long. In other embodiments the braid 382 can be longer or shorter.When packed into the delivery catheter, the braid 382 elongates. Forexample, the 2 cm long braid 382 can elongate to about 8 cm long whenpacked in the delivery catheter. The braid 382 provides a sufficientlylarge expansion ratio for a given volume of material. The expansionratio of the braid 382 typically is larger than the expansion ratio forknit or woven structures. However, knit or woven expandable structurescan be used in some embodiments. The motion of axially compressing thebraid 382 can result in a substantial diameter increase because tileindividual strands of the braid 382 are allowed to slide relative toeach other. In some embodiments, structures 380 can expand from about 6F to about 20 mm.

In some other embodiments, a braid 382 can comprise a serrated and/orabrasive material to provide increased friction against the wall of ahollow anatomical structure 320. In some embodiments, the braid 382 canbe inverted by pulling on one end of the braid 382. Inverting the braid382 can increase the radial force applied by the braid and/or increasethe diameter of the braid. Increasing the number of fibers in a givencross-section over the inverted length also increases the occlusiveproperties of the braid 382. Additionally, in some embodiments, aseparate component associated with the braid 382 can be formed to haveteeth or serrations in one or both directions. The separate componentcan be located on an outer portion of the braid 382 to improve frictionwith the vessel wall 320. In some embodiments, an expandable structure380 can be deployed at one or more portions of the implant 310. Forexample, one or more expandable structures 380 can be deployed at one ormore of a proximal portion, a distal portion, and an intermediateportion of the implant 310. Expandable structures 380 can provide acompletely endovascular fixation element for the implant 310. In someembodiments, the expandable structure 380 can be larger or smaller indiameter, and/or can have additional or fewer filaments based on thesize of the hollow anatomical structure 320. Where the vessel size issmaller, the expandable structure 380 can be made smaller in diameterand/or with fewer filaments to advantageously fit in a smaller deliverysheath.

According to another embodiment, a blunt inverse “V”-shaped anchor 383can be provided as a fixation element 302, e.g., as shown in FIGS.40A-C. The blunt head of the anchor preferably protrudes from thedelivery catheter and functions as an atraumatic tip. The arms collapseslightly while positioned within the catheter and expand when deployed.The ends of the arms are preferably bent outward to provide a bettergrip against the vessel wall. In some embodiments, at least a portion ofthe anchor is biodegradable.

According to another embodiment, a “U”-shaped clip 384 can be providedas a fixation element 302, e.g., as shown in FIG. 41. The clippreferably has solid rounded arms that collapse slightly when positionedwithin the catheter and expand when deployed. The ends can be moderatelysharp in some embodiments.

According to another embodiment, expanding wire loops 385 can beprovided as a fixation element 302, e.g., as shown in FIGS. 42A-C. Thewire loops preferably collapse during delivery and expand when deployed.In some embodiments, hooks are provided at a distal end to provideadditional anchoring to the wall of the hollow anatomical structure. Theanchor can comprise nickel titanium wire and can be coupled with PLAthread.

According to another embodiment, an expandable “sine wave” shaped stent386 can be provided as a fixation element 302, e.g., as shown in FIGS.43A-B. The stent preferably collapses during delivery and expands whendeployed. The stent comprises a solvent-sprayed PLA yarn in someembodiments. In some other embodiments, the stent can have a diamondshape 387, as shown in FIGS. 44A-B. A string can be provided to pull endportions of the diamond closer together, causing the intermediateportions to buckle outward and press against the wall of the hollowanatomical structure.

In some other embodiments, the stent can be a knit tube 388 forming afixation element 302, e.g., as shown in FIGS. 45A-C. In some embodimentsthe knit stent can be relatively short, e.g., about 2 cm long, as shownin FIGS. 45B-C. In some embodiments the knit stent can be longer, e.g.,up to about 35 cm or more, as shown in FIG. 45A. The knit stent likestructures can comprise PLA yarn sprayed with solvent, knit using 8plies on a four pin knitting machine. In some other embodiments, abraided stent 389 can provided as a fixation element 302, as shown inFIGS. 46A-C. The braided stent can be deployed before the implant isdeployed in some embodiments. The braid preferably exhibits someself-expansion. A pull string can be coupled with the braid to aid infurther expansion.

According to another embodiment, a multi-bristle expander 391 can beprovided as a fixation element 302, e.g., as shown in FIG. 47A-B. Theexpander preferably collapses during delivery and expands when deployed.The expander comprises a plurality of monofilament polymer bristles thatare moderately stiff. The combined effect of coupling the bristlestogether enables the expander to grab the wall of a hollow anatomicalstructure. The expander can comprise one or more bioabsorbablematerials.

Advantages of some embodiments and techniques using an expandable anchorstructure include the ability to combine delivery of the expandableanchor structure with the delivery of the implant in a single procedure.The expandable element is coupled within the hollow anatomical structureand relies on friction with the wall of the hollow anatomical structureto anchor the implant. Appropriately sized expandable structures can beselected. The expandable element may or may not be bioabsorbable.

Thermal Fixation and/or Vessel Shrinkage

As stated above and as shown in FIG. 37A, according to another aspect ofthe technique, securing the body 312 comprises thermally shrinking thehollow anatomical structure 320 near an implant location in the hollowanatomical structure 320. Implanting the body 312 preferably comprisesimplanting the body 312 at the implant location. For example, in oneembodiment, heat is used to spot shrink an approximately 1 cm section ofa vein near the sapheno-femoral junction. There are a number of ways toshrink a hollow anatomical structure 320. In one embodiment, apreferably self-contained and battery-operated heating coil can belocated on the outer surface of the implant delivery catheter. Thus, asingle catheter can be configured to perform the thermal shrink functionand the implant delivery function. The battery may be contained in thehandle of the catheter, or in a separate, rechargable power baseconnected to the catheter via direct contact or an electrical cable. Inother embodiment, any suitable energy tool and power supply can be used.In some embodiments, the handle can comprise one or more capacitors inlieu of, or in addition to, batteries. The energy delivered by a batterymay be controlled by use of a timed on/off circuit. The capacitor valuemay be selected such that it delivers the desired amount of energy whendischarged.

According to one technique for achieving thermal shrinkage, an implant310, a 6 F delivery catheter comprising a coil heater, a 6 F sheath anddilator, a guidewire, a pushrod, and a sharp are provided. The sharp ispierced through the skin, subcutaneous tissue, and hollow anatomicalstructure wall to access the interior of the hollow anatomicalstructure. The guidewire is inserted through the sharp into the hollowanatomical structure. The sharp is removed leaving the guidewire in thehollow anatomical structure. The dilator and sheath assembly is threadedover the guidewire and into the hollow anatomical structure. The dilatorand guidewire are removed, leaving the sheath in place. The implant 310is prepared for loading into the delivery catheter. According to oneembodiment, the implant 310 is a fibrous mass and comprises threestrands of 600 denier PLA. The strands are preferably doubled over,effectively forming six strands. The implant 310 in some embodiments ispreferably fused together at the tip with solvent to prevent blood fromsoaking into the implant and coagulating during the heating step. Theanchor string preferably comprises size 3-0 silk. In some otherembodiments, the anchor string preferably comprises Vicryl Rapide™. Theanchor string is coupled to the distal end portion of the implant with aknot. The anchor string is preferably interlaced with strands of theimplant along the length of the implant 310. The push rod can be aforked push rod formed from a 0.8 mm (0.03 inch) stainless steelmandrel. The implant 310 is preferably loaded onto the push rod. Thethree strands are preferably folded over the fork at the knot. The pushrod is used to guide the implant 310 into the catheter. The push rod isadvanced until the sheath and push rod tips match. In some embodiments,the push rod is advanced until a mark on the push rod reaches the sheathhub. The loaded catheter is inserted into the sheath. The catheter isadvanced to the proximal end of the desired treatment area within thehollow anatomical structure. In some embodiments, tumescent anesthesiais delivered to the treatment site to provide anesthetic, heat sink, andcompressive effects. The coil heater is activated by pressing a buttonon the catheter to deliver heat to shrink the hollow anatomicalstructure. The catheter is pulled back slightly and the outer sheath iswithdrawn. The implant 310 is exposed while the push rod is held inplace. Accordingly the implant 310 is deployed within the hollowanatomical structure behind the heat treated section. With the implant310 fully deployed, the push rod and delivery catheter are withdrawnfrom the sheath. Finally the sheath is fully withdrawn. Additionalfixation techniques can be performed if necessary and/or desired.Variations and modifications to the technique can be made.

The shrinkage may also be achieved via other thermal means such as aradio frequency (RF) emitting catheter (such as a VNUS Closure™catheter) or endovenous laser. Additional disclosure regarding heatingelements is provided in U.S. Pat. No. 6,401,719, issued Jun. 11, 2002,titled METHOD OF LIGATING HOLLOW ANATOMICAL STRUCTURES; or in U.S. Pat.No. 6,179,832, issued Jan. 30, 2001, titled EXPANDABLE CATHETER HAVINGTWO SETS OF ELECTRODES; or in U.S. Pat. No. 6,769,433, issued Aug. 3,2004, titled Expandable vein ligator catheter having multiple electrodeleads, and method; or in U.S. Pat. No. 6,638,273, issued Oct. 28, 2003,titled Expandable catheter having improved electrode design, and methodfor applying energy; or U.S. patent application Ser. No. 11/222069,filed Sep. 8, 2005, titled METHODS AND APPARATUS FOR TREATMENT OF HOLLOWANATOMICAL STRUCTURES; or U.S. patent application Ser. No. 11/236316,filed Sep. 27, 2005, titled SYSTEMS AND METHODS FOR TREATING A HOLLOWANATOMICAL STRUCTURE; or U.S. Provisional Patent Application No.60/613,415, filed Sep. 27, 2004, titled RESISTIVE ELEMENT SYSTEM. Theabove-mentioned U.S. Patents and Applications are hereby incorporated byreference herein and made a part of this specification.

Alternatively, external bulking agents can be used, as is shown in FIGS.48A-C. For example, FIG. 48A shows a vessel 320 prior to treatment witha bulking agent 390. As shown in FIG. 48B, bulking agents 390 can beinjected into a compartment surrounding a vessel to compress the vessel320. As shown in FIG. 48C, following treatment, bulking material 390 canbe absorbed and replaced by tissue. Bulking agents 390 preferably aremore viscous and comprise materials that are more long lasting thansaline. Materials injected into the perivenous space 392 near thesapheno-femoral junction can temporarily occlude the vein for a periodof days to weeks to limit implant migration and particle embolization.According to some embodiments, materials such as, for example, FloSeal,VNUSeal, and/or gelatin can be used if sufficiently large access, e.g.,6 F, is available. In some embodiments, TissueMend (degradablecyanoacrylate) and/or Atrigel (injectible PLA) can be used for smalleraccess sites. Additionally, in some embodiments, bulking materials 390can comprise yarn delivered for example by a continuous feed mechanismas described herein.

Alternatively, in some embodiments, the vessel 320 can be ligated fromwithin the vessel or external to the vessel to prevent migration. Oneembodiment includes an external bioabsorbable (or non-absorbable)ligation. clip 394 or suture to restrict the size of the hollowanatomical structure, as shown in FIG. 49. A reduction in diameter ofthe hollow anatomical structure acts a as flow restriction as well as aphysical stop for the implant 310. The implant 310 is deployed behindthe reduced diameter portion of the hollow anatomical structure 320.

Advantages of some embodiments and techniques using a thermal treatmentand/or vessel shrinkage include the ability to create a physical barrierto implant migration using the natural tissue of the hollow anatomicalstructure. A reduction in the vessel size results in reduced blood flow.Reduced blood flow improves coagulation and reduces the flow challengeto the implant. Positioning accuracy for the implant in increased.

Fenestration Anchor

As stated above and as shown in FIG. 37D, according to another aspect ofthe technique, securing the body comprises securing the body 312 with afenestration anchor 360. For example, in one embodiment, a fenestrationanchor 360 is similar in structure to the bioabsorbable tab 350, exceptthat the method of deploying the fenestration anchor 360 remotely andendoluminally from the access site 304 is more complex. In someembodiments, the deployment of the fenestration anchor 360 into a hollowanatomical structure 320, e.g., a vein, is similar to vein access usingthe Seldinger technique. However, instead of accessing the vein with aneedle, proceeding from outside the body to inside the vein, theprocedure is reversed. A needle-tipped steerable catheter can be used toaccess the perivascular space from a starting point inside the vein. Inone technique, under ultrasound guidance, the needle preferably ispositioned near the sapheno-femoral junction and punctures the veinwall. The dilating portion of the catheter and the implant deliverysheath are both advanced over the needle across the vein wall. Theneedle and dilator are removed, leaving the sheath lumen open to deliverthe anchor and implant. The fenestration anchor is deployed into theperivascular space and the sheath is retracted, leaving the fenestrationanchor on the outside of the vein. Further retraction of the sheathexposes the implant 310. As described above with the tab 350, thefenestration anchor 360 and the implant 310 preferably are connectedthrough the vein wall by a tether string 340. Additional through-wallfenestration concepts are shown in FIGS. 50-54C.

As shown in FIG. 50, according to another aspect of the technique,securing the body 312 comprises anchoring the body within the hollowanatomical structure by suturing the body within the hollow anatomicalstructure 320. For example, as shown in the illustrated embodiment, theimplant 310 can be anchored by a single or series of external sutures362 tied along the vessel 320 though the vessel wall and through theimplant 310 to hold it in place. This technique can be accomplished bysimple open surgical loops or by using a minimally invasive cannulaand/or needle delivered knots, clips, and/or staples by fenestrating thevessel and/or guiding the needle with ultrasound. In some embodiments,fenestration clips and/or suture knots 362 hold the implant 310 to thevessel wall. In some embodiments, a bioabsorbable stake or pin 364 canbe fenestrated through one or more walls of the hollow anatomicalstructure and through the implant 310.

According to some other embodiments, fenestrating coils 366, such asthose shown in FIGS. 51A-H can be used for fixation procedures. Forexample, in some embodiments, small coils can be deployed singly withthe aid of a needle and suture. In some embodiments, larger coils can bedeployed all at once by a delivery device. In some embodiments,fenestrating coils 366 can comprise nickel titanium wire havingrectangular or rounded cross sections. A large diameter coil can act asa filter for large particles as well as an anchor in some embodiments.According to another embodiment, as shown in FIGS. 52A-B a polymer coil366 can be provided in a fixation procedure. For example, a rectangularrod stock can be formed into a tight coil. The coil can be straightenedand inserted into a delivery catheter. The coil can then be pushed outinto a hollow anatomical structure where it regains at least a portionof its coil shape. In one embodiment the coil comprises polyethylene andcan be inserted through a 6 F sheath.

According to another embodiment, a barbed suture 368 can be provided asa fixation element, e.g., as shown in FIGS. 53A-B. The barbed sutures368 can be used for wound closures in some embodiments and for fixing animplant to a hollow anatomical structure in some embodiments. The barbedsutures 368 are preferably self-anchoring and may or may not bebioabsorbable in some embodiments.

According to another embodiment, as shown in FIGS. 54A-C, amulti-pronged expander 370 can be used as a fixation element 302. Theelement preferably has a plurality of thin, flat arms and/or prongsfixed at a first end portion, the arms bending away from one anothernear a second end portion of the fixation element 302. The element 302can be compressed for delivery and can expand upon exiting the catheter.The fixation element 302 preferably is coupled with an implant 310. Thefixation element 302 can be coupled at one or more of a proximalportion, a distal portion, and an intermediate portion of the implant310. In some embodiments, the expander 370 can have more or less thanfour prongs. In some embodiments, as shown in FIG. 54C, the tips of theprongs are sharp to enable the expander 370 to grab and/or penetrate thewalls of a hollow anatomical structure 320 when pushed forward.

According to one technique for deploying an implant and a fenestrationanchor, an implant coupled with a fenestration anchor, a needlecatheter, a 6 F sheath are provided. The catheter tip comprises aretractable needle. The needle is preferably retracted during initialinsertion of the catheter into the hollow anatomical structure. Thecatheter is advanced through the sheath to a proximal end of the desiredtreatment area. Tumescent anesthesia preferably is delivered to thetreatment area to provide anesthesia and to create a space outside thehollow anatomical structure to aim the needle and deploy the anchor. Theneedle is deployed and preferably locked in place. The needle catheteris advanced to pierce the wall of the hollow anatomical structure at thedesired location. The catheter and sheath extend outside the wall of thehollow anatomical structure. The needle is unlocked and retracted, andthe catheter is withdrawn leaving the sheath across the wall of thehollow anatomical structure. The implant is prepared for loading intothe delivery catheter. A forked push rod is provided. According to oneembodiment, the implant is a fibrous mass and comprises three strands of600 denier PLA. The strands are preferably doubled over, effectivelyforming six strands. According to one embodiment, the anchor is a 1 mm×2mm×10 mm bar with a hole through the center. An anchor string isprovided. An end portion of the anchor string is formed into a stopperknot to retain the anchor. Another knot preferably fixes a distal endportion of the implant about 5 mm away from the anchor point. In someembodiments the distance between the anchor and the implant can besmaller or greater. The tether string preferably is interlaced with thestrands of the implant along the length of the implant. The implant isloaded onto the push rod. The three strands are preferably folded overthe fork at the knot on the implant. The anchor is pushed into thecatheter. The push rod and the implant are fed into the catheter pushingthe anchor in front of the implant. The anchor exits the tip of thecatheter. The anchor preferably is completely deployed outside thecatheter while the implant and pushrod are near the tip of the catheter.In some embodiments, the anchor and tip of the sheath are preferablydoped with barium sulfate and/or air bubbles or other suitableindicators to make the anchor and tip more visible under ultrasound. Thecatheter is then retracted. Initially, the anchor will follow as thecatheter is retracted. The configuration of the anchor prevents it fromreentering the hollow anatomical structure. The implant is exposed asthe catheter continues to retract until the implant is fully exposed.Variations and modifications to the technique can be made.

Advantages of some embodiments and techniques using a fenestrationanchor include the ability to mechanically couple the implant with awall of the hollow anatomical structure and/or surrounding tissue. Theprocedure also allows for increased positioning accuracy for the implantcompared with some other techniques.

Retrograde Access Anchor

As stated above and as shown in FIG. 37E, according to another aspect ofthe technique, securing the body comprises anchoring the body at apercutaneous retrograde access site 306. For example, in one embodiment,a vein access site 306 is located near the sapheno-femoral junctionrather than near the knee or ankle. Other than the relative position ofthe access site, this technique is similar to the other access siteanchor techniques described herein and it can be combined with any ofthe other techniques as desired. The advantage of a retrograde accessover traditional GSV access is the ability to fix the implant 310 to thetissue at the proximal end, very close to the sapheno-femoral junction,thereby restricting movement of the implant 310 into the deepvasculature. The catheter used in retrograde access can have additionalfeatures to improve navigability across the vein valves. Such featurescan include a blunt, less traumatic tip profile, and/or steeringcapability.

Advantages of some embodiments and techniques using a percutaneousretrograde access anchor include the ability to mechanically couple theimplant with a wall of the hollow anatomical structure and/orsurrounding tissue. The procedure also allows for increased positioningaccuracy for the implant compared with some other techniques by havingan access site nearer the sapheno-femoral junction. Insertion of thesheath allows for a smaller incision than those used to perform ligationand stripping procedures. Accessing a femoral vein at the groin is acommon procedure and access to the femoral vein is easily achieved. Theneed to use an extra vascular closure device or extensive manualcompression for hemostasis is avoided because most of the flow isoccluded with the implant in place.

Wedge Fixation

As shown in FIG. 55A-B, according to another aspect of the technique,securing the body 312 comprises anchoring the body 312 within the hollowanatomical structure 320 by wedging an anchor element 372 within thehollow anatomical structure 320. For example, in the illustratedembodiment, an elongate member 372 is positioned perpendicular to a veinand is thereby wedged in place. In some embodiments, the elongate member372 can be made out of PLA, 50/50 PLGA, or other bioabsorbable polymerssuitable for injection molding. In some embodiments, the end portions ofthe elongate member are flat. In other embodiments, the end portions canbe sharp, pointed, and/or rounded.

FIGS. 56A-57C illustrate additional elongate members having alternativeshapes and configurations that can also be used in one or more fixationtechniques. For example, a tilting bar comprising a solvent sprayed yarn374 can be provided, as shown in FIGS. 56A-B. The tilting bar 374 ispreferably more flexible than the elongate member 372 described above.According to another embodiment, a swivel “T” structure 376 can beprovided as a fixation element 302, e.g., as shown in FIGS. 57A-C. Theswivel has first and second elongate portions coupled together such thatthe first elongate portion swivels relative to the second elongateportion. When the fixation element 302 is positioned in the hollowanatomical structure, the elongate portions can be swiveled such thatone elongate portion is positioned across the width of the vein wall andis thus wedged in place. The element can be actuated using one or moreof a string, a pushrod, or other suitable tool 308. Any suitablematerials can be used.

Plug Fixation

According to another aspect of the technique, securing the bodycomprises anchoring the body within the hollow anatomical structure bypositioning a plug within the hollow anatomical structure. For example,a preformed foam plug or foam sponge can be used in lieu of theexpandable element, e.g., the braid, described above, as an alternativefrictional anchor. In one embodiment, the foam is -coupled to theimplant. In some embodiments, the foam has the ability to block floweven more readily than the implant itself. The foam can be made ofbiodegradable materials such as, for example, polyglycolide,polylactide, poly-caprolactone, and/or copolymers of these materials.More information regarding bioabsorbable foams is provided by S. I.Jeong, et al, in a paper entitled “Manufacture of Elastic BiodegradablePLCL Scaffolds for Mechano-Active Vascular Tissue Engineering,” (J.Biomater. Sci. Polymer Edn, Vol. 15, No. 5., pp. 645-660 (2004)), whichis hereby incorporated by reference herein in its entirety.

Advantages of Fixation Techniques

Some preferred embodiments and methods for fixation are speciallyadapted to function in tapering vessel lumens to prevent migration ofthe implant. For example, mechanical anchors have the inherent advantageof functioning independent of the vessel taper. Additionally, anexpanding element can advantageously be adapted to fit a variablediameter vessel, for example, by expanding non-uniformly. Additionally,for migration prevention of the implant, flow reduction can bedesirable. Some techniques, such as the expanding braid and/or thethermal shrink techniques, have an additional feature of restricting theflow the implant is subjected to. The reduced flow has two distinctmechanisms for further reducing implant migration: The forces acting onthe implant are reduced and the coagulation that is part of the biologicocclusion process can take place more readily in the presence of reducedflow. However, in the acute healing phase, completely occluding flow canhave a negative impact on the efficacy of the migration prevention bycausing pressure build up which can cause the lumen to swell. This isundesirable in many cases because a swollen vein is more likely to bepalpable and less likely to be occluded without recanalization.Accordingly, in the acute healing phase, reducing the flow but notcompletely blocking the flow can be advantageous. In addition to theexpanding anchor and thermal shrink anchor embodiments, the implantitself also provides a flow restricting function.

Additional Delivery System and Technique

According to another embodiment and technique, an implant can bedelivered directly into a hollow anatomical structure without using adelivery catheter. For example, the implant can be pushed through thenative vessel using the pushrod. This provides the advantage of beingable to provide more space to accommodate additional fibers in theimplant because the implant doesn't have to go through a deliverycatheter that is smaller than the access sheath. Another advantage isthat in some embodiments, as the material of the implant drags along thevessel wall it is abrasive on the wall of the hollow anatomicalstructure, similar to other embodiments wherein an abrasive element iscoupled with the sleeve, the catheter and/or the implant to denudeendothelial cells to set up a more durable biologic occlusion.

Additional embodiments comprise methods of sterilization. Certain suchmethods can comprise sterilizing, either terminally or sub-terminally,any of the apparatus disclosed herein that are intended for insertioninto (or other contact with) the patient or that are intended for use ator near the surgical field during treatment of a patient. Any suitablemethod of sterilization, whether presently known or later developed, canbe employed.

Accordingly, certain methods comprise sterilizing, either terminally orsub-terminally, any one or combination of the following apparatus: theimplant 10/310 and/or any of the embodiments or derivatives thereofdisclosed herein; the delivery catheter 16; the pushrod 18; theocclusion system 200, including the fibrous mass 210, delivery member230 and/or sheath 232; and/or any of the fixation elements disclosedherein. Any suitable method of sterilization, whether presently known orlater developed, can be employed. For example, the method can comprisesterilizing any of the above-listed apparatus with an effective dose ofa sterilant such as cyclodextrin (Cidex(TM)), ethylene oxide (EtO),steam, hydrogen peroxide vapor, electron beam (E-beam), gammairradiation, x-rays, or any combination of these sterilants.

The sterilization methods can be performed on the apparatus in questionwhile the apparatus is partially or completely assembled (or partiallyor completely disassembled); thus, the methods can further comprisepartially or completely assembling (or partially or completelydisassembling) the apparatus before applying a dose of the selectedsterilant(s). The sterilization methods can also optionally compriseapplying one or more biological or chemical indicators to the apparatusbefore exposing the apparatus to the sterilant(s), and assessingmortality or reaction state of the indicator(s) after exposure. As afurther option, the sterilization methods can involve monitoringrelevant parameters in a sterilization chamber containing the apparatus,such as sterilant concentration, relative humidity, pressure, and/orapparatus temperature.

In view of the foregoing discussion of methods of sterilization, furtherembodiments comprise sterile apparatus. Sterile apparatus can compriseany of the apparatus disclosed herein that are intended for insertioninto (or other contact with) the patient or that are intended for use ator near the surgical field during treatment of a patient. Morespecifically, any one or combination of the following can be provided asa sterile apparatus: the implant 10/310 and/or any of the embodiments orderivatives thereof disclosed herein; the delivery catheter 16; thepushrod 18; the occlusion system 200, including the fibrous mass 210,delivery member 230 and/or sheath 232; and/or any of the fixationelements disclosed herein.

Conclusion

The above description discloses numerous methods, systems, apparatusesand materials. The inventions disclosed herein are susceptible tomodifications in the methods, systems, apparatuses and materials, aswell as alterations in the fabrication methods and equipment. Suchmodifications will become apparent to those skilled in the art from aconsideration of this disclosure or practice of the invention disclosedherein. Consequently, it is not intended that the inventions be limitedto the specific embodiments disclosed herein, but that they cover allmodifications, alternatives and combinations coming within the truescope and spirit thereof.

Except as further described herein, the embodiments, features, systems,devices, materials, methods and techniques described herein may, in someembodiments, be similar to any one or more of the embodiments, features,systems, devices, materials, methods and techniques described in U.S.Provisional Patent Application No. 60/605,843, filed Aug. 31, 2004,titled APPARATUS AND MATERIAL COMPOSITION FOR PERMANENT OCCLUSION OF AHOLLOW ANATOMICAL STRUCTURE; and in U.S. patent application Ser. No.11/212,539, filed Aug. 26, 2005, titled APPARATUS AND MATERIALCOMPOSITION FOR PERMANENT OCCLUSION OF A HOLLOW ANATOMICAL STRUCTURE. Inaddition, the embodiments, features, systems, devices, materials,methods and techniques described herein may, in certain embodiments, beapplied to or used in connection with any one or more of theembodiments, features, systems, devices, materials, methods andtechniques disclosed in the above-mentioned U.S. Provisional PatentApplication No. 60/605,843, and in U.S. patent application Ser. No.11/212,539. The above-mentioned U.S. Provisional Patent Application No.60/605,843, and U.S. patent application Ser. No. 11/212,539 are herebyincorporated by reference herein in their entireties and made a part ofthis specification.

A number of applications, publications and external documents areincorporated by reference herein. Any conflict or contradiction betweena statement in the bodily text of this specification and a statement inany of the incorporated documents is to be resolved in favor of thestatement in the bodily text.

1. An apparatus for treating a hollow anatomical structure, saidapparatus comprising: an implant comprising a plurality of bioabsorbablefibers; said implant having a compressed state in which said implant canfit within a cylindrical tube having an inside diameter of 8 French orless; said implant being expandable from said compressed state to anexpanded state in which said implant has sufficient size to span theinside diameter of a cylindrical tube having an inside diameter of 12French or greater.
 2. The apparatus of claim 1, wherein said implant hassufficient size, when in said expanded state, to span the insidediameter of a cylindrical tube having an inside diameter of 12-60French.
 3. The apparatus of claim 1, wherein said implant can fit withina cylindrical tube having an inside diameter of 6-8 French when in saidcompressed state.
 4. The apparatus of claim 1, wherein said implantcomprises a plurality of undulating fibers.
 5. The apparatus of claim 1,wherein at least a section of said implant is non-knit.
 6. The apparatusof claim 1, wherein at least a section of said implant is non-woven. 7.The apparatus of claim 1, wherein said implant comprises a fixationelement configured to limit migration of said implant when in saidhollow anatomical structure.
 8. The apparatus of claim 1, wherein saidimplant is self-expanding such that said implant tends toward saidexpanded state in the absence of external forces.
 9. An apparatus fortreating a hollow anatomical structure, said apparatus comprising: animplant comprising a plurality of bioabsorbable fibers; said implanthaving a compressed state in which said implant can pass through acylindrical tube having an inside diameter of 8 French or less; saidimplant being expandable from said compressed state to a treatment statein which said implant has a transverse size which is sufficiently largeto occupy an adult human greater saphenous vein of average size.
 10. Theapparatus of claim 9, wherein said implant can pass through acylindrical tube having an inside diameter of 6-8 French when in saidcompressed state.
 11. The apparatus of claim 9, wherein said implantcomprises a plurality of undulating fibers.
 12. The apparatus of claim9, wherein at least a section of said implant is non-knit.
 13. Theapparatus of claim 9, wherein at least a section of said implant isnon-woven.
 14. The apparatus of claim 9, wherein said implant comprisesa fixation element configured to limit migration of said implant when insaid hollow anatomical structure.
 15. The apparatus of claim 9, whereinsaid implant is self-expanding such that said implant tends toward saidexpanded state in the absence of external forces.
 16. A method oftreating a hollow anatomical structure having a diameter of 4 mm ormore, said method comprising: inserting into said hollow anatomicalstructure a catheter having a size of 8 French or less; passing throughsaid catheter and into said hollow anatomical structure a bioabsorbablefibrous implant; with said implant, reducing the patency of said hollowanatomical structure.
 17. The method of claim 16, further comprisingoccluding said hollow anatomical structure with said implant.
 18. Themethod of claim 16, further comprising expanding said implant to atreatment state within said hollow anatomical structure.
 19. The methodof claim 18, further comprising promoting occlusive ingrowth with saidimplant when said implant is in said hollow anatomical structure. 20.The method of claim 16, wherein said hollow anatomical structurecomprises a vein.
 21. The method of claim 16, wherein said hollowanatomical structure comprises a greater saphenous vein.
 22. The methodof claim 21, wherein inserting said catheter comprises inserting saidcatheter at an insertion site spaced from the sapheno-femoral junction,and further comprising advancing said implant from said insertion siteto the sapheno-femoral junction.
 23. The method of claim 16, whereinsaid hollow anatomical structure has a diameter of 4-20 mm.